Maybe if people looked at the bigger picture, there'd be fewer fractured families and less loneliness in the world.
This can work both ways round. There was a thread on here where the poster was struggling with her MIL. She kept wading in an controlling the Posters SD, and was having an issue with MIL storming in and tidying SDs bedroom. It seems like such a small thing, and I suggested some ways of negotiation, which the Poster took on board and tried.
It turned out that this was just the end stage of the MIL dominating, not listening, not compromising and undermining the Poster. The poster was still trying to fix one individual petty problem at a time. Unfortunately, a few months later, it culminated with the MIL screaming at Poster in the street and driving off with the Poster's 6 month old baby.
Yes - I should have seen the bigger picture. Tidying the SD's room turned out not to be petty at all, but one of a bunch of ways that she was controlling her DIL.
This 'People have to work on it!' thing is absolutely true. However, BOTH parties have to be prepared to work on it. I had issues with my MIL when I was pregnant with her first grandchild, and for about a year afterwards. Half of this was me not dealing with things particularly well. The other half was her being of the opinion that her way was best and quite pushy getting that into place. She is an exceptionally pushy woman, but she is NOT narcissistic. There is, of course, a difference.
BOTH of us worked at it. BOTH of us learned to respect the other one. Neither of us whined, cried, feigned illness and so forth to get our own way.
Things are good now - generally we get on well with some occasions that we don't. That's normal - I wouldn't expect either of us to have no character flaws.
If one party generally thinks that they do no wrong, that there's no need for them to change and compromise or even listen to the concerns of the other which are clearly nonsense, that it's not their fault that the other is getting hurt, that they don't mean these things personally, that the other shouldn't be so sensitive or shouldn't take all their 'jokes' so seriously, then that's when you see narcissistic tendencies coming through. They're ways of diminishing the other one, defecting responsibility and leaving all the work squarely at the other one's feet.
That's when there's a problem.
Anyhow, like flippinada, I'm looking forward to this list of threads where loads of people suggest NC over tiny things.