Idea for an erotic story

Greeting everyone,

This is my first post and I hope I am not violating any rules of this thread by posting a request for a story I would like to read.

Here is the idea:

I like (heterosexual) anal sex and want more of it. I think it is sexy, for the lack of a better word, to have sex that is not for procreation, but for the pure pleasure of it. I also like female butts, and I like the idea of transgression. It is something dangerous, and intimate because of it.

Now I also think that desire is such a thing that it also wants what it can’t have.

So combining these elements of my sexual fantasy, I would really like to read a well-written, reasonably realistic story about a man-woman couple engaging in anal sex, the man reaching an orgasm, naturally starting to lose his erection, but the woman determined to overcome the physical limitations of the male body and, driven by lust and the desire for the impossible, urging the man to stay inside and continue the anal act.