Instead of striving to be a perfect partner, concentrate on avoiding elementary mistakes. Studies have shown that people get relatively little credit for delivering more than they had promised, but they pay a stiff price for doing less. Before you make a commitment, beware what psychologists call the “planning fallacy,” our tendency to underestimate how long a project will take. Better to promise less and make sure you deliver on it than promise too much and fall short.

Another way to keep the peace is by fighting your own negative reactions to conflict. If your partner gets upset at what seems, to you, to be a trivial offense, remember that bad is in the eye of the beholder. You have to deal with their reaction no matter how irrational it seems—and the power of bad can bring out the irrationality in all of us. One critical word or careless affront looms much larger than any goodwill, and it will linger for longer, especially if you’re together 24/7.

When your partner does something that bothers you, don’t go with your gut reaction. Think before you blame, and be especially wary of what psychologists call the “fundamental attribution error.” When we do something wrong ourselves, we often blame it on temporary external circumstances: Yes, I lost my temper a couple of times today, but that’s just because of all the stress from the quarantine. But when our partner does something wrong, we’re inclined to wrongly attribute it to permanent internal flaws: He lost his temper because he has lousy self-control and doesn’t care about how I feel.

In 2000, researchers tracked couples’ “attributional styles” and found that attributing partners’ wrongdoings to internal flaws led to greater marital dissatisfaction and a higher likelihood of divorce. Before blaming your partner’s behavior on an inherent character trait, force yourself to consider a charitable excuse for what they did. And then give your partner the benefit of the doubt.

A friend of ours keeps his wife’s faults in perspective by taping a message to his bathroom mirror: You’re no bargain either. Being able to overlook your partner’s sins—to maintain what psychologists call “positive illusions”—is one of the surest ways to sustain a relationship. Some people seem to do it automatically, as demonstrated in couples’ brain scans. When shown a picture of their beloved, some people displayed less activity in the brain region associated with making negative judgments—and their relationships proved more likely to endure. But even if you can’t help spotting your partner’s offenses, you can at least pretend not to notice. As Ruth Bader Ginsburg’s mother-in-law once advised her, “In every good marriage, it helps sometimes to be a little deaf.”

If the affront is one you can’t endure, then say something, but do it calmly without retaliating, because the negativity effect can quickly turn a small disagreement into a raging battle. This dynamic was observed in experiments at the University of Chicago in which people took turns playing a game that gave them the option of either cooperating with their partner or acting selfishly. When a player acted benevolently, the partner typically reciprocated in kind. But when a player acted selfishly, the partner didn’t merely reciprocate—they tended to escalate the conflict by acting even more selfishly themselves. The Chicago psychologists summarized the participants’ reactions: “You scratch my back and I’ll scratch yours, but if you take my eye, I’ll take both of yours.”