We're kidding ourselves if we think that having sex with somebody that we had relationship with is not going to bring up feelings.
It was my first proper boyfriend so I felt like I was still learning a lot about relationships and kind of experimenting.
You shouldn't be fighting about anything one of you is doing wrong, because you should only be hooking up, right? It is a longing for circumstances that no longer exist or might never have existed.
People tend to have a lot of strong feelings about having sex with an ex.