Party on party conflict is bound to cause some stressors when it's over ethical questions - I've seen that before. I've even seen folks carry it over to the real world and get bent about it.

I knew one guy who always used to insist on running real bastard characters with little to no regard for human life and he, for some reason, expected everyone else just to tolerate this in game because it was 'just a game'.

Well naturally anyone running characters in the game were going to take exception to someone lasering a bus full of schoolkids or what have you (that was one of the things he did at one point) if those characters weren't of a similar sociopathic bent.

That was very strange and caused conflict too.