Why is it that when I know a girl with whom I have so much in common, and who always comes to me for advice, and who tells me things she has never told anyone before, with who I spend great time, long interesting discussions about art, philosophy and life in general, has great exactly the same taste in music, movies, art and books, and almost every time with whom I end up having crazy sex with... she says she doesn't want a relationship, although month later she has a bf? And when he dumped her, she comes back to me, not asking me back, just wants to spend time with. But why nothing serious?