I would say that's less 'constructive criticism' and more 'personal preference'.

Male engagement is just as much of an appeal to me as female. To me, the appeal of dominance and size is detached from gender - it's about a huge shift in power. The right male or female in that situation works just fine for me. The smirk on the male's face means he's not oblivious; he's complicit in the actions of his lover. She may be calling the shots, but he's completely okay with that. If this were a commission I was writing for you, I'd be happy to make alterations specific to your tastes... but this one was for me.

As for the maturity aspect... the woman about whom this was written is middle-aged; she's plenty mature, but she's still delightfully playful.

Cheers for the comment!