Why are people so hard

I have always been extroverted in school, I talk to pretty much everyone, but outside of school i have pretty much no one. I have one best friend who I’ve known for almost 10 years now. I used to have some acquaintances before covid, but after covid hit I completely chiselers them, and my family moved towns. I went to school for a year, but i didn’t really make any friends there. Well i did, but we don’t talk anymore… I can’t keep anyone in my life no matter how much i want to, or how much they try to be a part of it. I convince myself everyone hates me, and hangs out with me out of pity, and i don’t text anyone first- ever. I dont know how to create relationships, because it’s too hard. I never have enough time to hang out with people, and if i do i get burnt out in just a couple hours. The worst part is even with my own best friend, whom i probably wouldn’t be here today without sometimes is even too much for me. I love her so deeply, but I’m terrible with responding to others’ emotions. I end up being drowned in guilt anytime she’s upset because i’m a bad person for not being able to say the right thing. I know i’m only a teenager still, and every struggles with different things, but why couldn’t i just understand people? why couldn’t i have just struggled with math or something instead of relationships? i’m sick of feeling lonely and inadequate… I just want to be able to have friends.