Am i right to get mad? Honest opinion.

My boyfriend and I are international students in the USA and while I came here last fall, he joined in Spring this year, and we are still in the process of making friends. We're a total of 5 friends ( one of the guys was a good friend back home too, other we met here and it's been almost 2 months now)

Anyway, we share a common course and I often find them sitting in the library discussing the assignments without telling/ inviting. I did tell one of them once about including us, but i saw it on his story the very next day again.

Is it wrong on my part to feel bad about it? I wonder how I can make them include us? I miss the old days where you had a fixed group of friends and you used to hang out and study with them everywhere, and you knew they would never ditch you like this.

For context, all of us are Master's students at USC. It's not like they're not calling us coz we're dumb and can't keep us with them.

Am i being really petty?

P.S. all of you seem to think I'm being petty, and I should have made it more clear. We have been hanging out regularly together. Exploring places, going on trips, having house parties. We've been doing everything 'together', as a group! Then suddenly when it comes to studying, they've been excluding us.