What unites most of the relationships of friends, family, and random strangers I meet is the little niggles. An 18-year-old chooses a partner based on looks, a 30-year-old based on how they pack the dishwasher (the saying goes). Spending lots of intimate time with people naturally leads to a little dance developing. Steps we learn in response to irritation, moods, or just routine differences of opinion. My view is that you need to tend your buffer. There is no point in dealing with difficulties if you don't start from a foundation of kindness and respect. You need to like each other. In my experience, we take feedback best (particularly of the harsher variety) from people we have confidence are on our side. Feedback we know is intended to help because it is on the margin. It edges us forward rather than breaking us down. Start with kindness and respect.