I am in my early 50s and seven years older than my partner. She was 30 when we met and had had more than 20 sexual partners. Although our early sex life was good, she never experienced orgasms. Five years ago, she had an affair with a younger man, which I made her end. She was very angry about this, so in desperation, I let her sleep with him again, and subsequent lovers too. Amazingly our sex life took off. She became more open with me and she finally experienced orgasm. However, after her last affair ended, she switched off sex completely and will not even discuss it now.

You have been extremely understanding of your partner's needs, but sometimes such tolerance backfires. I get the sense that your relationship with her has a paternal aspect, and that familial quality is working against what you both really need: adult-to-adult love and sex. It sounds as if she has a child-like, needy quality - and, like a benevolent father, you "let" your partner (who is acting like a petulant teenager) have her boyfriends - for which she was savvy enough to reward you. However, this is not just about sex. Each of you may have deep-seated issues originating in childhood that have led you to be stuck in this painful impasse. Familial projections between partners usually shut down sexual desire, because they naturally arouse the incest taboo. I recommend you go for couples therapy - to help you move on from being a pairing of disappointed father and rebellious kid, to two adults capable of mature communication.

• Pamela Stephenson Connolly is a clinical psychologist and psychotherapist who specialises in treating sexual disorders.

• Private Lives appears every Thursday. You are invited to respond to this week's main problem. If you would like fellow readers and Linda Blair to answer a dilemma of yours, send us an outline of the situation of around 250 words. For advice from Pamela Stephenson Connolly on sexual matters, send us a brief description of your concerns. All correspondence should reach us by Tuesday morning: email private.lives@theguardian.com (please don't send attachments) or write to Private Lives, The Guardian, 119 Farringdon Road, London EC1R 3ER.