ending a friendship

never realised how unusual it was to not do friendship accounting/try to optimise social relations

not sure "abusive behavior" is necessarily accurate in all cases when they just might not be a great friend
I mean, if I did something genuinely irritating or socially abusive it'd be good to be clued in
I don't need a call or letter from someone when they decide to stop being my friend because I rebuke their political rants.