I have several:
1. I want to fuck my girlfriend in the ass but the times we tried, she gets nervous. Even if I use a lot fo lube an start slowly she doesn't like it.
2. I would like to fuck my girlfriend in front of another couple.
3. I would be ok with couple swapping with one oh her male friends from highschool. Once she told me that she had a crush on him. I know him, and I think he is a pretty cool guy, and besides her girlfriend has a geek/goth chick thing going on and I like that.
4. I have fantasized with 3 of my girlfriend's roommates. That they find us while we have sex and join. I know, it's a cliche.
5. I have a neighbor, she is a MILF. She does Yoga, Pole Dancing, vegan and she got a boob and ass job a couple years ago. I usually help her when she has problems with her computer. Everytime, I search for hidden sex videos or photos on her computer. No luck so far. Only selfies with her clothes on. One day I hope to find something "interesting" .
6. Recently an ex girlfriend came to town for a visit. When we were together she was a little chubby, but now she is fit. We ate and talked like old friends but I was only thinking in fucking her brains out for old times sake.
7. Also a couple of girl friends, one soon to be divorced and the other having sex issuess with her boyfriend, are searching someone to scratch their "itch" . I would gladly volunteer to do that, but one part of me would regret the decision inmediately.