One of the best ways to keep a marriage healthy is to maintain a system of mutual accountability within the context of love. This is done by protecting what I call the line of respect in a marital relationship. Let me illustrate.
Suppose I work in my office two hours longer than usual on a particular night, knowing that my wife, Shirley, is at home preparing a very special candlelight dinner. If I don't call to let her know I'll be late, you can bet that I'm going to hear about it when I get home. Shirley would see my behavior as insulting–and she'd be right. So she'd say, in effect, "Jim, what you did was selfish, and I can't let it pass." In those few words, and probably a few more, she would have spoken her mind in love and held me accountable for my disrespect. Then we would move on together.
In a healthy marriage, some things are worth defending, and mutual respect is at the top of the list. This doesn't mean you should nag, insult, publicly embarrass your mate, or point out insignificant indiscretions that should be overlooked. But a workable system of "checks and balances" can keep your marriage on course when issues of respect are at stake.
This kind of mutual accountability is the best way I know to avoid an unexpected explosion when stored resentment and anger reach a critical mass.