Claire increased the speed on the treadmill. She had been building up plenty of negative energy recently, and she was trying to make use of it to power up her workout.

"Whoa, girl," quipped her friend Megan, who was using the next machine over. "That's what I call trying too hard. You'll make me look lazy if you keep running like that."

"I'm just trying to blow off some steam, you know."

"'About what? Is it about your dad?"

The brunette nodded, her long brown hair tied in a ponytail swinging left and right. "You know I need to leave this Friday, right?"

"Yeah, how's he doing now?"

"Mom said he's getting a little better. He'll be bedridden for some time though."

"Sorry to hear that," panted Megan. One guy was deliberately slowing down as he passed behind the two girls to appreciate the show of their bouncing yoga pants-clad butts.

"It's alright. The one thing I'm most worried about is Bill. It doesn't feel right to leave him all alone for one week."

"For real, Claire?" giggled Megan. "Isn't he a big enough boy?"

"That's not what I'm talking about! Don't you get it?"

"I... guess?"

"I've been worrying about him cheating since I bought the plane ticket," Claire confessed.

"Can't he come with you?"

"That used to be the idea," said Claire. "But he ended up bailing out because he needs to save money to get a new computer, or so he says."

"Hmm-mm."

"The thought of our slutty neighbor learning he's going to be alone for a week is making me fume."

"How is she gonna know anyway?"

"I think she can hear our conversations through the walls, just like we can hear her fucking a different guy every night," explained Claire before muttering an audible sigh. "I bet she can't wait to put her filthy hands on Bill, now that I will be out of the picture."

The girls remained silent for a while until they finished their workout. They dried their sweaty faces with their towels and regained their breath before moving to the gym's lounge area.

They both got coffees from the vending machines before sitting on one of the benches. Megan had taken on a pensive expression.

"Something bothering you too?" asked Claire.

"No," she said. "It's just I remembered about something that might solve your problem, actually."

"What? An attack dog?" joked the brunette.

Megan smiled. "You know my sister works in a pharmaceutical company, right?"

"Uh-huh"

"Well, I think she has a pill that might just stop Bill from wanting to cheat on you," said the young blonde.

"They make loyalty pills now?" asked an incredulous Claire.

"Close enough. Know what, I'm texting her about it right now," said Megan, retrieving her phone from her bag.

The brunette shook her head. "I'm not sure what you're talking about, but whatever it is, if it can keep bitches away from Bill, I'll take it."

Megan giggled. "You free tomorrow? Let's meet for coffee after work and I'll show the thing to you."

Claire nodded. "Sure", she said, excited to find out more about this "loyalty pill".

*

One shower and car ride later, Claire arrived home. Her boyfriend was waiting for her as he finished some jobs on his computer.

"Hmm. You look amazing in this outfit," said the young man, admiring his girlfriend's curvy frame.

"Thanks, baby," she said before sitting on his lap. "Is dinner ready?"

"Yup. Just needs some time in the microwave." He held her in his arms, hugging her tightly. "Can't believe I'm going to not see you for one whole week."

"Oh, I'm sure you won't miss me," said Claire coldly. "Haven't you informed your second and third girlfriends already?"

The guy laughed. "Come on baby, don't be so silly." He kissed her on the cheek. "You know you're the one who's third in the ranking."

Claire lightly slapped him in the face. "You shouldn't even joke about stuff like that," she said.

"Fine fine," he amusedly said. "You get to be second since you care so much."

The girl tried to jump off his lap, but he held her tight. They french kissed before they went to the kitchen to finish setting the table.

*

Claire nervously opened the front door of the coffee shop where she was supposed to meet her friend. Looking around the busy café, she spotted Megan sitting at one of the tables in the back of the store. The blonde waved and Claire crossed the room to go and sit in front of her.

"I don't have much time today, so I'll get right to the point," said the girl as she searched for something in her handbag. Claire observed her intently until she handed her two pills.

"The loyalty pills?" asked the brunette.

"Not exactly," smiled Megan.

Claire had picked up the pills from her friend's palm and was studying them with her brown eyes. "What to do they do then?"

"I'm not sure if you heard of the pills that can shrink you. Those that are used in prisons and stuff like that."

Claire's face turned skeptical. "You want me to shrink Bill down?"

Megan grinned. "Sort of," she said. "These ones are actually a variation. They shrink you, but only when you have an orgasm."

Claire's eyes widened. "Are you… is this for real?" she stuttered.

The blonde girl nodded. "Put this one in Bill's drink tonight, then tell him what he just drank. He'll have to think twice about cheating on you."

Claire chuckled cheerfully. "I bet he will." She looked at the pills she was holding in her hand with newfound hope. "You're not pulling my leg with these things, aren't you? Will they really work?"

"My sister says they've been tested extensively. They haven't started selling them yet cause they're trying to solve legal issues first. But yes, they're 100% working. There's a market of BDSM and fetish enthusiasts that'll buy'em in droves."

"Really? People enjoy these kinds of things?"

"There's no shortage of weirdos out there," commented Megan. "But I guess in this case that's working out in your favor."

"But wait. How much will he shrink?" asked the brunette.

"According to my sister, it will depend on the strength of the orgasm. She said it varies from 10% to 60%, and possibly more if he's really going for it," she laughed.

"Really? 60% of his height in one go?" asked an incredulous Claire. "And they stack?"

"They do," nodded the blonde. "You might eventually find him ant-sized if you don't feed him the antidote soon enough."

Claire giggled as she fantasized about keeping an ant-sized Bill all for herself, away from all those good-for-nothing boyfriend thieves.

"Remember," said her friend. "White is the shrinking pill, yellow is the antidote."

Claire nodded. "How can I ever thank you for this?" she asked as she grabbed her friend's hands in her own. "You're a genius, Meg!"

"Just pay for my drinks in the next two or three months and we're set," Megan laughed.

"For now, let me take care of the bill," Claire said as she left some coins on the table. The conversation moved to fashion, food, and gossip for a few more minutes before the girls had to part.

"I can't wait to hear of how it worked," said Megan. "Call me as soon as you get back from your trip, alright?"

Claire nodded. The girls hugged and they both went their separate ways.

*

"I'm home," announced Claire. Her boyfriend was working in front of his computer, as usual.

"Hey babe," he said. "Welcome back."

"Thanks, sweetie."

For a while, as he finished his daily work, she just hung out in the living room watching TV. When he finally joined her, she decided it was time to get serious with her plan. She went for the fridge and returned with two opened beers. The one she handed to Bill had been tampered with the pill she had just received from Megan.

"Thanks," he said as he began to gulp down the drink from the can.

"You're welcome," she smiled. She put her hand through her hair, watching him drink the "magic" beer.

"Is this really going to work?" she pondered, her heart racing. Once Bill would have drank the tampered beer, there was no coming back.

They were going out for dinner for their last night together before her departure. When they came back from the night out, they sat on the sofa for some late-night TV watching.

"I'm going to have to tell him sooner or later..." she thought, as Bill's attention was caught by an action movie. "But first, I want to make sure Megan was not bullshitting me."

She moved closer to Bill and started unzipping her pants.

"Whoa..." he said as she started massaging his member.

"Shhhh." His dick quickly rose to its full size as Claire's expert hands began to rub it up and down.

"You're good," he moaned, giving in to the pleasure the hands of his girlfriend were offering him. She knew exactly which buttons to push, and it didn't take long for the girl to finish him off. Cum drizzled like a fountain on her hand and his shirt.

Then Claire watched him closely, her mind racing from the suspense as she waited for the pills to work.

Bill felt weird. The pleasure from the handjob he received had turned into a very unpleasant sensation, one remotely similar to dizziness that he couldn't otherwise explain with familiar terms. "Am I getting sick?" he wondered. He strangely felt like his clothes were getting roomier too.

Claire, on the other hand, was triumphant. She was witnessing the effects of the medicine in real-time. She felt his member, which she still was holding in her hand, escaping her grip. His tight shirt looked oversized on him now, and his whole silhouette shrank as he sat on the sofa.

"Bill... do not freak out," she whispered. "Everything is going to be fine."

"Huh?" he said. "Actually I'm not feeling too well. Did you notice?"

Claire smiled slightly. She kissed her boyfriend on the mouth. "It's okay," she said. "There's one thing I need to confess to you."

"If it's about the fact you ate the last donut, I already noticed. Um, hey Claire? You look bigger. I must be dreaming." The familiar face of the brunette was towering over him and something about the whole situation definitely felt off to him.

"I'm not bigger," said the woman. "It's you who turned smaller."

"What..."

The girl rose, and she pulled Bill up from his hands. They were standing at roughly the same height now.

"How?" said Bill, the events way too overbearing to process for his slightly drunk brain.

Claire giggled. "I couldn't stand the thought of leaving you alone for one week, Bill. I couldn't accept the idea you might have cheated on me without me ever finding out. So I got this pill... it shrinks you down every time you have an orgasm."

"What?" He looked at his girlfriend, horrified. He was eye-to-eye level with her. What she had just said was simply unbelievable, but the fact that he had actually shrunk proved otherwise.

The girl curled her lips. "Come on Billy... don't be like that. Say something."

"This is... this is not right. You can't do this to me," he lamented. "You're a psycho."

Claire shook her head, upset with her boyfriend's reaction. "I'm just protecting myself. I know there's plenty of evil bitches who are ready to jump on a taken man."

"Claire! I'd never cheat on you!" he cried. "Why can't you just trust me?"

Claire put a finger over his mouth. "Shhhh," she said, before kissing him. For a while, Bill was bribed by the wet kiss he shared with his girlfriend, but eventually, he returned to protest.

"How can you do something like that without my consent," he cried. "What if this thing was dangerous?"

"It's not. Believe me, Bill, I wouldn't put you through danger for nothing. And besides, when I'm back next week I'll give you the antidote so you can go back to normal."

"What do you mean, next week? I am shorter by, like, several inches, in case you didn't notice. How am I going to live like this?"

"Just like I do?" said Claire. "Being, huh, five foot four is not a big deal. Just make sure you don't cum again before I'm back," she giggled.

He shook his head and sat on the sofa looking for comfort. "But this is mad! How am I going to be able to even go out like this? You need to give me the antidote right now."

"Sorry but no way," said Claire who was getting fed up with her boyfriend's protests. "The sooner you accept it, the best."

"None of my clothes will fit," he cried.

"Big deal. They'll just look a bit loose, you fashion freak."

"I can't believe you thought this was an okay thing to do," he sobbed.

As she looked at his crying face, Claire was starting to feel sorry for him. Had she really gone too far, feeding him the shrinking pills? No, she thought, that wasn't right. She had done whatever was necessary to prevent him from cheating on her. Any sane girl would've done the same, she reassured herself.

"Come on big boy. Stop crying, look at these," she said, taking her shirt off and proudly displaying her plentiful breasts to him. But he ignored her.

"He must be really upset if he won't even react to boobs," she thought. "Oh well... it'll pass."

She left him alone and walked to the bedroom. First, she removed her pants, remaining in her white underwear only. Then, she started preparing the bags for the next day.

Half an hour later, he joined her in the bedroom. "Feeling better?", she asked, seeing that he had stopped crying.

"I'm still mad," he rebutted. "How did you even find those pills?"

"That's a secret I won't tell," she said. "But don't worry, I am sure they are safe."

"Yeah, right. Except for the part where they make smaller. So how do they work, exactly? Every time I come, I shrink down? So if I orgasmed again, I would lose some more height?"

"Huh-uh, wanna try it out?" she said as she inched closer to him, putting her hands on his thighs.

She was certainly alluring. But Bill was still upset, and moreover, he wasn't certainly interested in any sexual activity if the result would've been him dwindling down again. So he broke free from his girlfriend's grip.

"No," he refused. "And I'm sleeping on the couch tonight."

And he meant it. Claire, who was already tired, decided she didn't have the energy to go and change his mind, so she went to her bed and rapidly fell asleep.

The following morning, she was ready to leave for the airport. Bill seemed to have mellowed down a bit after a night of sleep.

"You're leaving?" he asked. He had started working on his project early in the morning.

The brunette nodded. "How about a goodbye kiss?"

The man complied. "What you did is still wrong, you know," he said. "I don't know how I'm going to deal with being this short for one whole week. I'll have to hide at home, as I don't want anybody to see me like this."

"That's kind of the point," thought Claire. "It's a good thing you work from home, then," she told him instead.

"That's the only upside. That, and the fact we're stacked on food."

"Now, I really need to go," said Claire. "Be on your best behavior. I don't want to find you any smaller when I come back."

He sighed. "Hey, Claire."

"Yes?"

"Can't I even jerk off then?"

The girl shook her head. "Not unless you want to shrink down." She liked the sound of that. She found it was empowering. She was the only one who could allow him to orgasm, he was forced to abstain as long as she was gone.

He sighed again. "Let me help you with these bags."

He lifted one of her bags, noticing how heavy it was to him. Other than his size, he had surely lost some of his strength because of that pill. When he walked out of the building and got out on the street, he felt like everyone was staring at him. After he parted from his girlfriend, he came back home and closed the door behind him. That was going to be one long week.