In the first chapter, I can't help but remember a Monty Python joke. 'American Beer is like having sex in a canoe, f---ing close to water.'
Read the story now
All jokes aside, I like how you've actually been able to include some plot and some relationship development into erotic fiction.
A few points, your paragraphs are very long and could use shortening.
You say that each chapter is a short story, but actually, if you pad it about with a bit more description, the first story could actually be a short book on its own, maybe a novella?
One part that I find confusing, is how you keep on jumping between the past and the present, particularly towards the end. One moment Mark and Monica are in the canoe, the next it's their first time together months before, this jump happens several times. I understand why, but maybe just have one longer flashback, rather than many shorter ones?
I really hope this can help you, keep up the great work, Sofia