Adult friendships require GRACE. They’re not ignoring you or “being weird” they’re battling something mentally. It’s not always personal because they couldn’t make your birthday. I’m sure they wanted to but finances maybe made it not possible. You have to think beyond just you.
One thing I realized is that everything always ends up working out. Sometimes even better than you can imagine. Remember this when you feel like you're in a hard place or you feel like you're being challenged the most. Believe in where you're headed. See the bigger picture.