I’m in my early 50s and am starting to find my wife not sexually attractive any more. Over the years she has gradually put on weight to the point she now weighs more than me; I’m 6ft and normal weight for an athletic, active man. I’ve got mixed, conflicted feelings about it.

On a physical basis I don’t like it, but she’s now started walking with a different gait and I find myself disgusted and pitying her. On a medical basis, it can’t be good long term.

I have mentioned it in the past and asked her to make lifestyle changes, which last three to four weeks. It’s making me feel resentful and not respected. I feel as if I shouldn’t have to ask my wife to be a reasonable weight. But I’m simultaneously avoiding the issue because I don’t want to humiliate and upset her. How to address this?

Eleanor says: I’m going to set aside your concerns about your wife’s health. Partly because – as I’ve written before – there’s evidence people can be healthy regardless of their weight. Mainly though, it sounds as though the way this matters to you isn’t primarily to do with her health.

If it were, we should also be talking about her sleep habits, stress levels and carcinogen intake. It sounds like the way this matters to you is that you find her less attractive.

Long-term monogamy asks us to find one person attractive, instead of all others, in perpetuity. This is hard. We all change as we age, and maintaining a marriage will – if we’re lucky! – mean we’re still excluding all others when we’re liver-spotted and all out of collagen. Attraction shifts a lot in the intervening decades, and it’s OK to struggle with those transitions.

You say you feel “disgusted” and “not respected”. It sounds like weight is wrapped up with a lot of moralised failures for you; like you attribute laziness to her, slovenliness, disregard for how you experience her. This just isn’t a good inference. People’s weight changes for all kinds of reasons, especially as we age and our hormones change.

Why does her weight make you feel this way, rather than any other “lifestyle change” or feature of her appearance? Do you also feel you “shouldn’t have to ask” her to maintain her hair, her clothes? What about sleep, which is also a huge predictor of long-term health and possibly day-to-day attractiveness, too?

What if she someday feels disgusted and disrespected by your greying hair, your wrinkling skin, your loss of muscle?

It’s one thing to struggle with finding your partner attractive. It’s another to ascribe a failing to your partner in light of that; to feel contempt for them, or like they are beneath you. It will be vital for the viability of your marriage that you’re able to separate these feelings.

That’s true even purely from the standpoint of self-interest, too. Nobody is a bigger freak in the sheets and more excited to invest in attractiveness than somebody who thinks their partner worships them. And nobody tries to hide their body away and recoils from touch more surely than someone who can smell their partner’s contempt.

Glamour, sexiness, investment in yourself – these all require a degree of confidence that your effort will be worthwhile; that you won’t be humiliated by being judged and found wanting even with your red lipstick on. She will be able to tell that you feel disgusted by her. I promise you this will not lead her to aspire to being “less disgusting”.

Attraction waning is one thing. But don’t confuse that for a moral insight about your wife. If you cannot separate those feelings, you’d do her a kindness by leaving. But you may regret the conflation of appearance and moral value once your own body begins to change under you.