Because of this, my husband has at times fretted that I might leave him. What should he do with that anxiety? Maybe eroticizing it isn’t the worst strategy, especially if it gets us talking about what turns us on and keeps us in the loop about each other’s lives. Surely it’s better than the more mainstream reactions to jealousy: becoming paranoid or controlling.

Meanwhile, what should I do with my attraction to other men, especially to this one handsome friend? I knew the technically proper route: I should have pushed him out of my life as soon as I realized I was drawn to him. I shouldn’t have e-mailed him so much. I certainly shouldn’t have made plans to see him alone, at night.

And yet, being married to someone who likes that you want other people (and that they want you) muddles the question of whether to have that late-night drink. If the goal of avoiding extramarital temptation is to protect your marriage, but you have been led to believe that occasionally giving into temptation could be O.K. for your marriage — possibly even good for the home fires — what should you do?

Maybe every so often, when someone comes along who’s especially appealing, and who seems to understand your situation and respect it, and whom your husband for whatever reason does not feel threatened by, you kiss him. Then the next day, you feel alternately thrilled and ashamed; and then when your friend doesn’t immediately respond to an “Are we O.K.?” text, your shame tips into despair.

Years ago, my husband told me he had fallen in love with someone else. He was deeply confused and scared by it. I didn’t even know who he was talking about; that’s how much of a secret he had kept his growing feelings. When he told me who it was, a co-worker, I felt as if I had been shot. I broke things. I threw him out. He ended the affair. Since then, I’ve forgiven him, and we’ve worked hard to figure out why it happened and what it meant.

The main thing that helped me get over the affair was realizing that attraction to other people isn’t necessarily a sign your marriage is bankrupt. In the course of being together forever, especially if you’re out in the world meeting new people, it happens. One of the challenges in a marriage, in addition to deciding whose job it is to do the dishes and how to balance the budget, is to figure out how to deal with lust or love for other people.