I think you just may be looking for the wrong things in people and not seeing their trueselves, or just looking int he wrong places for friends/gf's. Of course, it's still hard because people [u
always change as time progresses, you learn more and more about them, it's like that with
everyone, not just some people. This is a hard question, but I think it's because everyone tries hard in the beginning to be a bit better than they really are to impress their friends/gf's, and in the end their true self comes out. But that's only what I think.
Oh, and pretty much everyone has issues. Some are just more visible than others, some people just admit they have them more than others, and some people just have worse issues than others. But everyone has them!
