Well, from my experience it is woman that do this more often than men!

Some of us tend to pay attention to a number of things, including what you're saying. We also tend to concentrate harder on things that may bore you, so... I, personally, have NEVER met a girl I could be "so attentive to" "then next thing [I] can't stand to even talk to her"... If someone is doing that to you, consider that they may have "got what they wanted" and now could care less what you say, if you understand my meaning. It MIGHT appear I'm ignoring you, because I'm paying attention to something else, and, if you stop talking for a while, and I get into a game, the computer, or TV, then you start talking again, PLEASE, don't expect me to hear EXACTLY the first few things you say. I will listen, but might not have heard the exact words you were saying. ALSO, don't start talking in a normal tone of voice and "drop off", and expect that I can hear what you say from 10 feet away. Just because I say "What" doesn't mean I didn't hear MOST of what you just said, and it doesn't mean I need a hearing aid! ;-) No all guys are the same. Please don't believe that. That's why it just takes one guy to ruin it for all the others, because girls tend to think that.

They got what they wanted and no longer see reason to engage ones self with her.