I am a happily married man of more than 20 years, with a wonderful home and life that I would not change for anything. I met and married quite young and – while I enjoyed various sexual encounters before settling down – have always had a nagging feeling that I missed out on certain experiences. Some are quite ambitious, such as a threesome; others are more mundane, such as a one-night stand. I do enjoy my sex life but am sometimes overwrought by thoughts that I never “completed the album”, as it were. I am starting to resent people who have had more experiences, as if it’s a competition, even when I know that other aspects of my life have turned out far better than theirs. While I am happy, and would never dream of venturing outside my marriage to address a probably overexaggerated wish list, how can I get rid of this overwhelming feeling that I have missed out and there is a gap I will never be able to fill? Try to see these thoughts as fantasies – wonderful expressions of healthy eroticism that can serve as a means of keeping you sexually alive – and even enhancing your sexual drive to be intimate with your wife. Please do not take this to mean that you should fantasise about other people while making love with your wife … it is best to be truly present with her. I mean that fantasies serve a purpose – either to facilitate arousal, masturbation, or a general sense of private pleasure and sexual vibrancy. Unfortunately, you have connected these feelings with regret and a sense of longing, and you are not alone in that. Studies have shown that most people think about and fantasise about having sex with someone other than their spouse. Fortunately, you seem too smart to bow to peer pressure or risk losing the life you have for what is really just an ephemeral notion. Pamela Stephenson Connolly is a US-based psychotherapist who specialises in treating sexual disorders. If you would like advice from Pamela on sexual matters, send us a brief description of your concerns to private.lives@theguardian.com (please don’t send attachments). Each week, Pamela chooses one problem to answer, which will be published online. She regrets that she cannot enter into personal correspondence. Submissions are subject to our terms and conditions. Comments on this piece are premoderated to ensure discussion remains on topics raised by the writer. Please be aware there may be a short delay in comments appearing on the site.