I think guys never really fall for a girl completely unless a) he trusts her b) she meets his needs c) he is ready to settle down, whether he is concious of that or not.
Because I've sure heard stories. One of my guy friends was dating a girl for 4 years, she wanted to settle down, he didn't. He said he loved her, but they just parted ways, never to speak again. NEVER SPEAKING AGAIN! (is that even loving somoone? I know it hurts but I wouldn't like to not speak to someone I love). I asked him what it means to be in love, he said I was a close understanding or connection. So what happened there? it just stops? Another guy friend just had random sex in bars or whatever came along, until he met some girl working in his store, and they starting to see each other, and one day she asked to move in with him and theyve been together ever since. And he is 'settled' into the relationship, he doesn't go to bars anymore or drinking and stuff. he's domesticated now. I asked him what men look for in a relationship. And he said it was obvious. He mentioned looking good, and being able to cook.
I think you just have to happen to be the right thing at the right time for some of these men. Come to think of it, I wouldn't want to be with either of these friends, its so insulting. With some other kinds of men, its more just a connection you have it or dont. But men seem to explore their options more than women do. Women are more choosy, men arent. with some men, nearly anyone showing interest has a shot. And some of these relationships work. I have known people from high school who started dating a guy who was not so into them, but they have ended up together all these years, simply because it was the type of guy who doesn't bother to date around, or they learned to love each other.