Don't do or say anything that will lead to a fight or argument. Don't do anything that creates a negative environment.
To this I would add "unless it involves one of my own core boundaries." The way it's stated above always SOUNDS good, but far too often I see people here using that as justification to DO NOTHING, including protecting their own and their family's core boundaries of personal integrity, be they legal, financial, emotional or sometimes even physical.
The best advice I ever got in my sitch, I got very early on, and it said that instead of doing things from a perspective of "What will my wife think if I do thus-and-such? Will it make her angry? How will her reaction make ME feel?" and instead replace it with "In every situation, do the thing that God Himself would have you do, if he were standing right in front of you, and don't worry about your wife's reaction to it."
Put more simply, it all comes down to "Pick your battles." Yes, you blow off the small stuff, and even on the BIG stuff you remain pleasant and civil and you don't enforce boundaries from a position of simply being a dikk. But sometimes you DO need to enforce them, regardless of the anticipated blowback.
