High or Not, Maintaining Relationships Debate At 8

Is there any helping AJ's friend that's perpetually single? He recently called it off with a girl because she was 'too high maintenance' but when asked how he just said 'You know what I mean.' How would you define it? And why does the phrase make McCall mad? Can you be friend's with an ex? One listener has a BFF that was an ex but the new boyfriend is super against any hanging out 'because those feelings could come back.'