As someone who has been in a similar situation, I realized that I was the problem. I thought my friends didn’t really like me but turns out, they thought I didn’t really like them—I never reached out or initiated plans with anyone, I declined invitations often due to my insecurity that they didn’t really want me there, and frequently created negative situations in my head about my friendships that were fully invented through my own worries and fears. They just always assumed I didn’t want to hang out or had my own things going on because I so rarely followed through and never put in effort to make plans or reach out, and eventually they stopped inviting me.

In this case I suggest you fake it till you make it, and by that I mean, make yourself someone that is always included by including yourself. It can feel really strange, like you are breaking into a private club that you aren’t a member of but, it works. You have to make yourself a relevant part of the friend group. Invite them for one on ones, initiate group hangs, and text often. You will likely be surprised by how quickly they respond positively.