What comes after talking to a girl for long?

Maybe they don't know what to do with a girl or how to "get with her". I lot of younger, well, a lot of guys in general, have no idea how to embrace a women.

Or after talking with a girl for a why, he decides, "eh, I'm not really as into her as I thought. I'm done with that. ".

Or some skanky girl will bed the guy down fast and hard and makes him become her boy friend - this is more common then some may think.

Is this question saying, "Why do guys spend so long talking to a girl, saying you like her, and then not getting together with her"? If so, here's my answer.
Some guys want to get the feelings off their chests (let her know, but start nothing romantic). I liked a girl once where we would chat happily for an hour or so a day. I liked her, and she might have liked me, I don't know. I eventually decided to tell her how I felt, despite the fact that I wasn't ready for a relationship. Things were too hectic in my life, not least of which was the fact that we were in a full time course that sometimes required full nights of work. All I could do was tell her how I felt, but nothing more. I felt that it was only right she know how I feel as it affected the way I acted around her.

Well, like most guys. I think, I try to get to know the girl first and then I am always waiting for the "right moment". Believe me, it is a lot harder than it seems, especially if you really like the girl. My advice to you is that you should drop a big hint on the guy because that is probably what he is waiting for.
Hope I helped!