The dilemma Several years ago my (then) 67-year-old grandmother got involved in internet dating, obsessing over an American man who later transpired to be a scammer. Then, two years ago, we started hearing about Kumar, who she said she met while on holiday. She’s been to “visit” this man dozens of times, travelling from our rural town to London, often for weeks at a time. Elaborate stories are invented: he is a multimillionaire involved in a lengthy divorce; he owns a company in Houston; he sent a limousine to collect her for care by his private doctor when she was sick…

If disagreed with she storms off shouting that nobody respects her. Pictures of Kumar have appeared around her house, but never the two of them together. I looked into her phone and found Kumar does exist, but only as a person on a dating site who she exchanges dirty pictures with. We used to be close until she started concocting a double life for herself. We are all worried for her safety and mental health.

Mariella replies I’m intrigued. Is her penchant for a fantasy life with a man she meets only online so worrisome after all? She’s not only an adult, but a mature one at that, and if she wants to go out in a blaze of romantic glory, even if it’s mainly make-believe, who does it hurt?

I appreciate it’s hard for you to watch her weave a tangled web of deception and rather puzzling that she feels it necessary to do so. But so many others are watching their grandparents descend into the emotional desert of dementia, or laid up in hospital with an illness that can’t be cured, struggling to cope when their bodies give up on them long before their mental faculties have – or vice versa.

Your grandmother has embraced new technology, embarked on escapades, is living independently and sounds pretty capable of concocting sophisticated stories. What she’s up to may be mystifying, but it’s also quite magnificent that’s she’s got the energy, zest and desire to keep it up.

The question really is what is “it”? If Kumar doesn’t exist as a real-world dalliance, who is your grandmother spending all this time away with? Could it be that Kumar is simply a decoy and what’s she’s really up to is even more subversive?

It’s curious that, having discovered her boyfriend is only an online simulation of a relationship, you’re not as intrigued as I am about where she’s spending her real time. Invading your grandmother’s privacy by perusing her phone is an extreme thing to do if her only crime is leading an unorthodox love life.

I’m as puzzled by your possibly inappropriate level of interest in her personal life as I am by what she’s up to. If there is a mystery to clear up, it’s what’s going on during her prolonged excursions, not who she’s playing temptress with in cyberspace.

The latter really is her business. As we age we often revert to childlike behaviour. It’s why grandparents often get on with toddlers far better than they did as parents. We can also become increasingly self–centred and determined that it is our way or the highway, as seems to be the case with your grandmother. So, perhaps it’s the same infantilised approach you need to take?

If a child makes up a story, we tend to humour them and go along with the narrative. Why not treat your grandmother similarly? Try playing her game by telling her you’ve bumped into Kumar. Say you recognised him from his photo, had a great chat and have invited him down for the weekend to meet his extended family. Tell her what a lovely guy he seemed to be and that you’ve got a couple of possible dates to run by her. It could be just the jolt to prompt her to come clean.

Otherwise, I’m afraid it’s down to less imaginative means. A gentle chat about how much you miss being close to her might open up a less confrontational conversation, bearing in mind how little of this is really your business. Kumar may just be a distraction to keep you off the scent and her life could be an even more multilayered narrative than you already imagine. Or she may be feeling lost, alone, deceived and eager to confess, but in need of your encouragement to do so.

The internet is a great place to lead a fantasy life – but it’s less helpful if it’s real flesh and blood connection that you’re after. Those not reared on the dangers of cyberspace may be naive in their embrace of it.

Ultimately your concern is impressive, so long as it’s not simply control of her that you’re after. I’m sure if you approach her with love, you’ll find the right time and place to open that discussion. But do remember, it’s her life, she’s run it for a long time and the accruing years don’t mean she has no right to continue in just the same vein.

I have to say, the complicated web of deceit aside, I’m rather impressed by her energy for adventure.

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