If those people aren’t for you, then I think it’s best to just take a break from them for however long you need. You don’t have to be stuck with them, it’s okay to make new friends, even if it might take longer than expected. As an introvert, I understand what you may feel like, though I’m trying to make new friends from the new environment I’m residing in. It’s easier said than done, but the process pays off!
Also, if you don’t know how to make other people feel better, it’s not a bad thing. After all, if you want to care about someone else, you have to care about yourself first. It’s like building a building: you start with the foundation (you), and then you can start building the other parts (caring about others after you did to yourself)! If you’re not always available, then that’s perfectly fine, you don’t always have to be there for others, they can be there for themselves too.
Take care, man! :]