This has been going on with me for like 2 years. I befriended a "straight" girl and, within a month, she was flirting with me and telling me it was her plan to sleep with me. I told her I didn't mess with straight girls, but then we got closer and closer emotionally and essentially became best friends. We texted all the time and saw each other every weekend. It was very much like we were dating.
At the 3 month mark she spent the night over my house and propositioned we sleep in the same bed. Nothing happened, but I woke up in the middle of the night to her spooning me pretty hardcore. In the morning she got up to pee then came back to bed and cuddled me more.
This cuddling in bed continued for several months, growing in intensity each time (hands on thighs, thighs between thighs, her breath on my face etc.) but we never had sex.
Besides that she was always looking right in my eyes, in a romantic way, sitting right up on me, standing next to me so that our bodies touched, and just generally touching me all the time.
She then got a BF and put an end to it. But...some months later she decided she wanted to have a threesome with me and another guy who wasn't her BF! The threesome wound up being me having sex with her and her having sex with the guy. Afterwards she just went back to her BF like nothing had ever happened! Oh, and we went back to cuddling in bed.
She broke up with her BF another few months later then flipped out on me over the cuddling/sex etc. Total gay panic! We stayed friends but it was weird for a while.
Then she started messing around with the threesome guy but, as soon as he developed feelings for her, she split.
Nothing happened between us after that for a long time. Then, about two months ago, she started getting really touchy and affectionate with me again. We went out together one night, got drunk, and had another threesome! Meanwhile she is screwing some other guy.
So I got upset and confused, confronted her about her behavior, and she denied all responsibility. She simply said "It just happens when it happens." Then said she cannot give me what I want.
Now we are not really speaking and I still have yet to get any answers. I miss her friendship and I'm always sad, despite it being screwed up, and I wonder if I should have just kept my mouth shut...