I am a 66-year-old woman 11 years out of a 30-year marriage. My husband left to live with the woman he had been having an affair with, but the marriage hadn’t been right for some years and our sexual activity had diminished drastically. I have a male friend who is the same age as me and we are friends with benefits – only the benefits don’t work. He can’t penetrate me. Either I have shrunk or he is just a big lad (after 30 years of monogamy, I am not exactly au fait with penis sizes). It makes me feel sad and inadequate. We pleasure each other in other ways, but it would appear penetration is off the table. Before I consult a doctor, what am I doing wrong?

You are not doing anything wrong. In fact, it is wonderful that you understand the erotic value of non-penetrative sex. Some men with atypically large penises struggle to find women who can accommodate them, but it is not certain that your friend falls into this category. After a long period of abstinence – and most likely hormonal diminution – some women do experience some vaginal atrophy that restricts penetration with a penis of any size.

Consider experimenting with gentle self-penetration once you are aroused through masturbation (use lubrication); this may help you understand your current genital physiology. But most likely, if you want to receive penetration comfortably again, it would be wise to consult a sexual medicine professional who may be able to help. Typical treatments include hormone therapy, sex therapy and vaginal dilation.

Pamela Stephenson Connolly is a US-based psychotherapist who specialises in treating sexual disorders.

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