Some people

are like, one moment, they're really chilled, they give you birthday presents, they hang out with you, text you and stuff, do some stuff that makes you feel special, share secrets, tell stories, take picture together.

And then like 3 months later they don't do that anymore. You're pissed off (obviously), you feel awkward and weird. It's not only because of them not doing stuff anymore, it's also you don't put any effort on it. You stopped trying. You stopped talking and all you do is just wishing that everything's running well in their lives.