Intermittent reinforcement was discovered by the behavioural psychologist BF Skinner in the 1950s. He conducted experiments with animals that revealed if they were given a treat every time they pressed a lever, they pressed it only when they were hungry. However, if the treats were given randomly at unpredictable intervals, they pressed the lever obsessively, almost to the point of exhaustion.

Humans are exactly the same. The brain releases dopamine in anticipation of a reward. When the reward is unpredictable, anticipation increases, which releases even more dopamine. Intermittent reinforcement and the pursuit of dopamine are the reasons we use slot machines, scroll incessantly on social media and persist with relationships that feed us occasional crumbs of love and much larger doses of disdain.

It could be one of the reasons that your wife is initiating more sex. Not knowing whether you will be in the mood only serves to increase her appetite. If sexual rejection makes her question how much you desire her, that will compound the problem. 

Marrying her self-worth to whether or not you will have sex with her only heightens the intensity of her desire. It’s a very complicated psychological scenario, one that you could unwittingly exacerbate every time you do, or don’t, agree to have sex.

To find a way forward you need to look backwards. What has changed? Why are you not in the mood? When did your wife start initiating sex more frequently? How come you are so tired? 

The answers to those questions might reveal issues with your work-life balance, your health, financial stress, hormonal changes or unresolved conflict in your relationship, and the process will help you to understand why there appears to be a mismatch between what your wife wants (love, sex, validation) and what you want (TV, cocoa, slippers).

Lots of couples have less sex as they get older, and if they are both on the same page and at the same stage, it isn’t necessarily a huge deal, but physical intimacy carries emotional weight and when it changes or disappears, it can feel like a loss of connection or an absence of desire.

Initiating sex is your wife’s way of bidding for connection, and I very much doubt an orgasm is her sole motivation. If you spoke honestly to her you would probably discover that what she wants as much is your attention and your affection. If you genuinely want to “meet in the middle and avoid hurt feelings”, try making time for her. Make her feel loved. Be tender with her. Make her laugh.

There are myriad ways to meet her need for closeness and intimacy — sleeping naked, snuggling on the sofa, holding her hand, or rubbing lotion into her back — which show you are making an effort to do tiny things that let her know that she is cared for. 

The opposite of intermittent reinforcement is continuous reinforcement, so instead of pushing your wife away, be consistent, be present, be honest, be available and leave no room for her to doubt your commitment.

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