I'm 38 now and I no longer enjoy all the interactions with my friends that I used to. Often once we get started I can get into it, but the thoughts I have in advance come up like a cost-analysis proposition in my head. Part of me is convinced that socialising with friends is work. I know my friends have started to feel the same as they've gotten older too.

I blame things like instant messaging for making those baseline friendship interactions too easy and too disposable and too convenient.

My response is to get out there and I socialise anyway. If someone makes efforts to be friendly to me I man the fuck up and return in kind and I recognise the way I feel for the fault that it is. It's a dead end that leads to unhappiness. Hanging out with people (not just your friends, ANYONE) is like exercise for your mental health. The more you hate and dread it the more you probably need it so it's best to just get it over with because it'll become easier with renewed practise.