I've recently become "just friends" with a girl that I was with before. I'm not pissed or anything as I was planning on breaking it off with her but she beat me to it, I just wanna know what is likely to have caused it, so I don't mess up again in the future.
Here's the scenario: I gamed her on a night she was staying over my residence with a friend, kiss closed her and then went to sleep and she went back to sleep in my friend's room, we kept seeing each other a few times a week and making out and me giving her oral for a while back and forth at my residence and her's. I let her know I didn't want a serious thing because all the guys I knew who had a serious thing ended up whipped and I didn't like confinement. After a while we tried sex too painful for her the first time the second time we slowed down and actually got it done (she was a virgin). Right after the sex was a break where we both went away for around a week. Saw each other once after that with a bunch of other friends so nothing happened. Next time I saw her maybe a few weeks later (which I took as flaking, but she was actually busy), she was distant and I didn't let it get to me, and before she left (her and a few friends had to get somewhere) she told me that it'd been too long and we were just friends. This seems strange to me for a few reasons:
1-A friend told me when she talked to her she really seemed to miss me when she was real busy.
2-I gave her good sex and was her first.
3-We seemed really good right before the vacation.
Not sure if this sounds like oneitis or whatever but I'm over her (already hitting on other chicks, some of whom are her friends

), I'm just trying to figure out what happened so I can avoid it in the future.
Thanks