Why do guys ditch their best friend for their girlfriend?

[Erashad]

A couple things could be going on here. (I'm assuming you're a girl the way you talk btw)

First off, in regards to your overall question,, it would be completely normal for you guys to not be as close as you once were since he got a girlfriend. I can't speak for this guy but most aren't really interested in being friends with girls and now his girlfriend is his best friend maybe.

Still however this doesn't explain why he wouldn't wave to you or respond to your birthday text. It could either be he really just doesn't care much and he got a bunch of texts and only responded to half of them, or maybe he heard you said something about him.

Either way he doesn't sound like much of a friend, I'd let him contact you from now on. Study hard and make money.