The dilemma I’m 77 and have been married for 54 years. Seven years ago, I delivered the eulogy for a childhood friend. Afterwards the lady next to me held my hand and said, “Good job.” On impulse, I later found her phone number and called her. It was the start of a seven-year affair. She knew I was married. She was separated and later divorced her husband. I told her that divorcing my wife was out of the question. Also, I said eventually that someone would come along and steal her heart and that she would leave me.

Our relationship was wonderful. In time she mentioned that she would like more. Even asked what it would be like if we were together all the time. I brushed these questions off, usually. I thought it was an ideal situation for both of us. She had grandchildren to look after and her daughter was going through a difficult marriage. Our relationship was not going any further. She turned 72 and I knew she was concerned about getting older.

Well, it happened. Her only sibling passed away and a childhood friend – who she dated 50 years ago – came to the funeral. Afterwards she told me they were in love and that he was her soulmate. I bid her farewell and good luck. We have not communicated for four months. Do you think she’ll contact me?

Mariella replies Well, this is unusual. First, it really is a whole new way of looking at what have been described – perhaps erroneously – as our twilight years. I used to regret the passage of time, as the births, engagement parties and wedding invites dried up and hospital visits and funerals laid a greater claim on my diary. Now I’m seeing the Eulogy Years in a whole new light. Who knew the whole funeral business was such a hotbed of recoupling? Perhaps since you now have a vacancy you should go to them more often, not just to say goodbye to old friends but also acquaintances, neighbours, even being a pew-filler at the ill-attended rites of strangers. Judging by your experience it sounds as though the heightened emotional atmosphere isn’t just energising the mourners to sing the hymns more fervently.

The late Jimmy Goldsmith famously said that marrying your mistress creates a vacancy, and there’s obviously an empty space that you remain eager to fill. That means it wasn’t just an accident of timing and chemistry that spurred you into the arms of the lady in question but, rather, an unspecified and still unfulfilled need.

I have to be true to form and sensible here. Why are you still with your wife? Do you see it as the decent, noble thing to do, despite your infidelity? Perhaps you’ve reached some sort of agreement that weighs the longevity of your union against indiscretions. You do sound like a casual Casanova, determining the boundaries of the relationship based on what suits you best. Is it possible that, even in your late 70s, you were just in it for the sex? If so, I don’t know whether to whoop for joy that the libido can “rage, rage against the dying of the light”, or curl up in exhaustion at the prospect of having to keep going for another two decades.

I suspect you’re not writing to me for my wise words on extra-marital relationships but because you think I’m psychic! Sorry to disappoint, but I have no idea what your ex-mistress is likely to do. Your three short paragraphs are not enough to give me a clear idea of how this total stranger is likely to respond now that she’s found a less furtive relationship.

What I can say is that you’ve had a pretty good innings. An enjoyable seven-year affair that’s left your wife none the wiser seems a pretty good result. You wouldn’t be human though if you didn’t want more. This inclination not to count our blessings but to want to increase them seems as natural as breathing to Homo sapiens. Having brushed off this woman’s attempts to make the liaison less ephemeral, you’ve now discovered what happens when that’s all you want. You won’t be the first man to learn to appreciate your lover once they’ve gone. Truly there really are only two courses of action. The first requires you to get in touch with this woman and admit that her absence has left you longing for contact. Though what you have to offer that she hasn’t now got is hard to surmise. The second is to thank your lucky stars for what you had and what you got away with and determine to inject a little of whatever it was that affair offered, even if it’s simply sex, into your marriage.

To be revealed as a philanderer at any age is no great compliment but for it to happen when you truly are old enough to know better is bordering on embarrassing. My guess is that you’re a decent man who’s stuck with his partner through life’s ups and downs and, ironically, those are the very qualities that make you attractive to others. For my money that’s a far better legacy than chasing around after a woman who clearly wants what you’ve already got.

If you have a dilemma, send a brief email to mariella.frostrup@observer.co.uk. Follow her on Twitter @mariellaf1