Is it normal to want to be with some one very badly.

This always seems to happen to me. I'll meet someone and well be talking, and we click very well. I eventually fall for this person and couldn't really see myself not being with them. Then when we start dating. After a while, I loose complete interest and sometimes I have gone to the point where I can't even stand to look at them. I feel maybe it's a emotional wall. But I thought sooner or later if find someone where I haven't had this happen to me. But it does every time. I dated one girl for a year, and the only reason it lasted that long was that I'm in the military, and had changed
States so I didn't get to see them often, then recently she's been meeting up with me. I had to break up with her because I just couldn't stand being around her anymore.