Many here have separated and then after a period of time noticed the conflict seemed to be less or even gone, the ex seemed relatively normal from a distance (the first quote) yet when they reconciled and got back together the prior conflict resumed (the second quote).
Absolutely right - and one of the most frustrating aspects of their condition. We start to think 'are we finally getting through to them?' but then once we're back together the cycle starts over again. Can't win either way. First time my exBPD broke up with me it wasn't until 9 months later that we started going out again... took her about a week to start her BPD antics again, like the break had never happened.
As for the second quote 'Familiarity breeds contempt', I've always found this true even when dealing with all people generally. Family and lifelong friends get to see all of me, while people I know casually - like other customers I chat to in my local pub - know me to a far lesser degree, which means there's never any conflicts and everyone's always happy to see each other. Sometimes in life, less is definitely more.