Getting into scraps online because it's the only form of socialisation they can get where they get any validation (through either people agreeing with them or feeling superior to the people they're arguing with). Lurching wildly from social group to social group to get that initial high of meeting new people attention. Alcoholism. Breaking keyboards and mice due to losing at video games and then continuing to play those video games (and losing a bunch). Typically, a lot of behaviours that mean they remain isolated even if they don't necessarily do anything untoward. You can probably think of a bunch of examples off the top of your head. It is self perpetuating to a degree.

I would be cautious about this topic since some things that would come to mind are arbitrarily culturally/class defined (maintaining a nice haircut, wearing suits etc), and some are autistic traits. I'd want to focus primarily on behaviours that harm social relationships that wouldn't be performed if they had all their social needs met. Obviously, men are neither trained to handle this well nor recognise it within themselves.