None. If it’s an excuse they’re not friends. You have reasons to cancel or you don’t. “Hey, I need to take a mental health night. I’d make it if I was in the right headspace. Sorry.”

I know from experience most of my “friends” in my teens and twenties wouldn’t accept that. Today, I either get “alright, we’ll catch up” and then we catch up or I get an offer “I just wanted to hang with you. Would it help if I just brought over a couple of beers?” Life gets real and real friends get that.