toxic friends and your experiences

I used to stay in hostel and I had my 3 roommates who became really close because of me. I always tried to connect them wherever they fought and i always initiate the hang outs, party and stuff. But they always cancel on me. Not only them, I will always try to hang out with my school friends but they would always cancel on me. I didn't think about it that much cause I had an online friend and I always vent to her. But I coudnt help but feel super left out cause my 3 roommates would be posting stuff in their stories about how they r so proud to be a trio and how all 3 of them r bestfriends and they never mention me. And one time, I wanted to have a secret santa party at my house and i invited a whole lot of people and it got cancelled yet again, and then I found out they all hung out without me, and the party was arranged by my three former roommates. So yeah this is how I'm always left out. But I still have my online friend so I guess I'm ok