(Image: BBC Essex)

A married couple from Essex, Debbie and Tony Dowsett, say they go away on dates, have sex and go away with other partners. In an interview today, Debbie told BBC Essex that “we don’t see it as anything strange at all, its been the key to our long and successful marriage”.

I’m not convinced.

It’s one thing to say you are happily married. But once you dig beneath the surface of any marriage, you find always differences and difficulties and misunderstandings that have to be managed on a day to day basis. Most of these are papered over and forgotten. Occasionally issues flare up and lead to arguments or a drifting apart. That’s the everyday ‘for worse’ part of marriage.

It’s hard enough making a marriage work with two people. It’s unimaginable how it can work with more than two people for a sustained period of time.

At our core, we are all fundamentally selfish. Some more so, some less so. But almost all of us crave an intimate relationship with another adult who will give us reliable love.

That’s the dilemma. How do you trust that somebody can give you reliable love when they are fundamentally selfish like you! You and they may both be wonderful people. But everyone has their bad moments. A successful relationship needs to account for those bad moments.

So at some stage, you need to come to a mutual agreement that conveys some sense of reliable future.

You can’t do that with a conventional contract: if I do this then you do that. A contract is not reliable love.

You can only do that with a promise, better still, a promise made not in private which either of you can deny or forget, but a promise made in public, where your friends and family can be proud of you and also hold you to account.

That’s broadly speaking why marriages tend to work more than unmarriages. There’s a clarity about a shared plan for the future that allows each of you to put up with each other’s foibles, differences, misunderstandings and bad moods. A clear sense of future allows you to sacrifice for each other, without expectation, and forgive one another when you blow it – as you will.

Marriage between two people goes with the grain of human nature. There’s no guarantee of success. But the odds are now in your favour because you’ve chosen a method of affirming your relationship that allows for your weakness, difference and bad moments.

Marriage specifically copes with ‘for worse’.

Now make that promise – with all of the sacrifice and forgiveness that you will need to give – to a person who also wants to retain the freedom to sleep with others.

Did both of you reach that conclusion equally? Or is one of you slightly more selfish and has persuaded the other that this is a good thing?

Marriage between two people is a completely equal relationship because it is so clear that both partners are signing up to the same plan. How on earth does that equality apply in an open marriage or polyamorous relationship?

Nonetheless, good luck to Debbie and Tony. So long as it’s not hurting others, and not involving very confused children, then fine.

I remain sceptical.

Relationships are hard enough between two people. Even with the promise, 35 per cent of marriages fail. Without the promise, 75 per cent of cohabiting relationships fail.

What hope between three or four people?