Ok, so this is something I've just begun to struggle with recently. I have a woman that I've started to really like and it might get much deeper. I really like her and I have gotten close to her over the past year. Well, we started up a relationship recently and all has been going well. Except I cannot get my mind to stop thinking about her previous relationship.

Yea...I don't know why I got fixated on that. But for some reason when I think of them (they were together long ago and do not communicate) and their sex life it disturbs me. They had done things I haven't done, which is part of it--and whenever I think about words she used to describe those interactions it bothers me. And now it's starting to interfere how I feel about her--I don't want to feel different about her like that but I don't know how to make things click in my mind and put it to rest. I tried telling her to see if it would help--but she told me to not think about it, which has resulted in me thinking about it more.

How to fix this? What's going on in my head?