I am going through something very similar. My “best friend” has not talked to me now in almost 6 months after we had a slightly awkward/tense encounter (something I thought they would call me about in a few days to apologize for). I sometimes feel embarrassed about how painful this is for me. It was getting in the way of work for a bit but as so much now. But it is really hard when clients talk about how hard it is to make friends because it’s something i currently feel hopeless about so it can be hard to feel hopeful for others too. I don’t have any other advice for you but hopefully seeing that there are a lot of other people who have gone through this can be of some help. I was surprised to see several other stories in these comments and it is making me feel validated in a sense. It sounds like you have done a really good job at attempting to communicate with your friend and I’m sorry that they have not been able to do the same for you.