We have had a good sexual relationship for nearly 50 years – not bad going when you’re in your 70s. After three children came the contraceptive pill, a wonderful period in our relationship. You felt completely free to enjoy making love, and the pill relaxed you so much that reaching orgasm was scarcely ever a problem. Then the menopause arrived and the pill could be abandoned. At the same time my sex drive began to diminish. Since we had both enjoyed sex so much, we wanted to continue. The answer was for me to take Viagra.

At first, it was half a pill. After six months, two-thirds. Then three‑quarters, until finally I had to take a whole one. For a while it seemed that a glorious new lease of life had begun. But I noticed I would be tired out for half a day after taking the pill. One day, I made the mistake of mentioning this. You were worried sick that I’d suddenly drop dead as both our fathers did: they died with no warning at 49 and 50. You have a mental list of women friends whose husbands inexplicably and suddenly died. You told me we’d had a better sex life than most of your friends, and that at my age I shouldn’t put my life at risk.

I argued that my tiredness after taking the pill was no worse than how I felt after a game of squash, a five-mile walk in the country or digging over the vegetable plot. I want to go on taking the pill until it doesn’t work for me. I’m not ready for such a dramatic change in our relationship – but you clearly are. The matter rests there, like a huge, invisible wall.

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