I recently re-watched the long version of Scenes from a Marriage. A couple sees other couples around them in trouble, smugly feels safe, and then learns that they are not. A lesson not lost on the attentive viewer. The details are quite realistic, making the whole thing painful to watch.

The obvious big question is: what went wrong? And for that one need only watch the first 2 of the 6 episodes, on the period before the breakup. Which is in my mind the most realistic part of the movie. After the break, we see explosive and hurtful conflict, and hear titillating stories of promiscuity, but see less insight into the breakup.

The man initiates the break, and while he has several complaints, his biggest seems to be that she’s become too reluctant to have sex. She’s also been expressing unhappiness and seems to suggest (perhaps unconsciously) that he should give her more better attention. He suddenly declares he’s in love with someone else and is leaving. She is shocked, thinking she could read him better, and that he would talk before making such a decision. She begs him to let them try again, but he refuses.

If we see a marriage as a deal that can be continually renegotiated, then a simple interpretation here is that he saw her as grabbing better terms in their deal, by giving less while asking for more, and she moved past his limit, i.e., his reservation price. He didn’t try to explicitly negotiate over sex, instead of just leaving, plausibly because begging for sex makes us seem less attractive and we want our sex partners to be sincerely eager for us, instead of reluctantly accommodating.

It may seem sad that, even after knowing each other very well for many years, we can’t predict each other better to avoid such destructive outcomes. But in fact this unpredictability seems essential to the process. If we each knew the other person’s exact limits, then we might try to push them right up to but not past their limits. Making them unsure of our limits makes them wary of pushing us too far. And when your partner can read you very well, not knowing your own limits may be the best way to keep them from knowing.

So even with the people we know best, we don’t know their limits, nor our own, which warns each of us against pushing too far to grab more for ourselves at the expense of our partner. Don’t trust to your ability to read them, or expect to get a warning and or a chance to retreat should you push them too far. Treat them well, and be wary of our bias to remember our resentments for longer than our gratitudes.