Dislike

Have you ever gotten the distinct impression that someone doesn't like you?
I am experiencing this for the first time in my life. Not that everybody likes me or anything. There are some people I don't necessarily "click with" or whatever, or people who maybe didn't like me but didn't show it so actively. Until now, I haven't gotten the serious feeling that someone is avoiding talking to me, and really doesn't like me, FOR NO APPARENT REASON.
A very long time ago, I was dating this guy and he was about to leave for boot camp. We'd known each other for several years but had been dating for only about six months. This one girl, his ex-girlfriend and longtime best friend, made him a scrapbook to take with him. She went around his good-bye party and had everyone EXCEPT ME sign his scrapbook. And he and I had been friends, too, for several years -- I know that if I hadn't been dating him, she would have asked me to sign the damn book. At that time, I knew she was just mean, and didn't like me, but at least she had a reason. It was a dumb reason but at least I knew why.
This person who doesn't like me right now just all of a sudden decided not to like me. All of a sudden, this person doesn't want to talk to me. I know this person is avoiding me but I don't know why. And it kind of hurts my feelings.
MrDartt says it's character-building for people to not like you. After all, he says, lots of people don't like him, and look how much character he has. True.
And when someone doesn't like you, and you see this person regularly, are you supposed to ask why this person doesn't like you? Are you just supposed to let it go? Are you supposed to ask someone else why this person doesn't like you?
And I know I shouldn't care if someone likes me or not, but I DO!
I TOTALLY CARE!
Does this make me lame?