My closest friend and I have known each other for over 20 years. Both of us has changed a lot in that time but we still really get on, and we make each other laugh like nobody else.
Ever since I started a relationship 18 months ago, and especially since I have got engaged, she's been very distant. There are various personal issues in my life and work at the minute, and not being able to talk to her has made me feel enormously sad and lonely.
She's had a rough time with relationships, still really isn't over the last serious one that ended 2 years ago, and is increasingly obsessed with, and distressed by, the idea of not finding 'the one' and starting a family before it's too late (she's 34).
If our friendship group of women wants to arrange a meet-up, she will specify that she won't attend at all if people's partners also come. In a situation where there are lots of couples in the mix she feels like people are looking down on her for being single.
Because of where people and their partners live (causing travel/timing issues), that means we pretty much don't ever meet up, or we meet up without my closest friend. She rarely agrees to meet with me one on one any more (maybe once every few months).
It's all come to a head because, after trying to arrange a group Christmas get together to which she flatly refused to come, again, I gently pressed her whether we should talk about this issue - more than anything I wanted to be supportive and hated to see her hurting still after all this time.
She flew off the handle. She said she had the right to avoid things that make her unhappy, and this is just how things were going to be from now on, forever. And that I had obviously forgotten what it was like to be miserable. She seemed really angry with me, which really took me aback.
She's meant to be my only bridesmaid at my wedding next summer. I haven't really been able to do any girly wedding planning stuff because she's been so off about everything and I don't want to annoy her further. I just want us to be excited and have fun together 
. I don't know where to go from here. At the moment I think she would be a lot happier to not have to play that role. But if I tell her now that she's excused from being maid of honour I think that would be the end of the relationship, no matter if my motivations were kind.
Any guidance on how to tackle this would be much appreciated. Even though I thought I knew her well, I obviously don't, otherwise I would have been more capable to help her than this. I may as well ask strangers on the internet!