The dilemma I am in a sexually open relationship with my partner of six months. This has always worked in the past, and we have always communicated openly and honestly with each other. Recently, however, he expressed to me that he wants me to see other people romantically, not just sexually, instead of seeing just him as my “primary” partner, because he is scared to commit. I know that he has low self-esteem and often experiences feelings of inadequacy. He fears that he will be replaced, but he also fears commitment, because of the promises and expectations it holds and because he is scared that he will disappoint me or fail me. We have tried monogamy in the past and it is not something we want to try again, but I fear that he is using polyamory as a way to hide his insecurities rather than addressing them head-on, and using a lot of flimsy excuses to shield himself from the truth. I know that he loves me, but he is also terrified. What do I do to support him and get over this fear?

Mariella replies Basically he’s human! You list all of your boyfriend’s emotional foibles quite extensively, but perhaps he’s not the only one using “flimsy excuses” to shield himself from what’s in front of his nose. There are often good reasons posited for dysfunctional lovers, but sometimes it’s a less complicated scenario than we try to paint it. I’m not taking a position on “polyamory”. Plenty of people swear that consensually putting sexual trysts beyond your “primary” relationship on the menu keeps passion alive. Clearly you rank among them and you say it’s worked up until now. Then again, it’s hardly a long-term relationship. I’m not being judgmental, but I’m betting you’re quite young. Describing the machinations of a six-month relationship as “the past” and using words like “always” to refer to that short period when judging the relative success of your open sexual arrangement otherwise seems fairly self-deluding.

In the great scheme of a lifespan, your relationship is in its embryonic phase and certainly at the point where you’d normally have eyes only for each other, not one still scanning the room for a more promising sexual performer and negotiating get-out clauses for further romantic exploration. If your boyfriend now wants to include romance on his bucket list of unfulfilled desires, my interpretation is that he’s sending you a clear signal that he wants to be, or should be single.

What he’s suggesting seems barely a friendship with “benefits” – and who stands to gain isn’t clear. It’s certainly a bonus when you’re single to have a friend or two you can rely on for flirtation and sex when the pickings are slim on the more elevated romantic front. In my experience there’s usually a winner and a loser in such situations; the one who enjoys the benefits and the one who works hard to maintain the friendship. I maintain an open mind when it comes to the myriad manifestations of human love and desire, but when you’ve found someone you connect with uniquely, what’s the advantage of remaining on the market? It suggests what you’ve found may be diverting, but it’s not consuming enough to prevent distraction.

The less you’re prepared to invest in a partnership, the less valuable that union will ultimately be

Some people are prepared to settle for being tolerated in exchange for ultimate freedom, but it wouldn’t work for me. You need to be confident and secure in yourself to be able to cope with the regular missiles that will be lobbed at your sense of self-worth. The people who can withstand such an emotional barrage on a regular basis are in a minority and made of sterner stuff than the rest of us. Personally, I like a few constants in my life and one of them is the security – as much as any of us can depend on another person’s presence in our lives – of a long-term partner. But it definitely involves compromise.

What fun to welcome each new day with the possibility of an unexpected sexual adventure, but how do you mitigate for the disappointment when you are the one who’s second choice? In most aspects of our lives you only get out what you put in, hedge-fund managers aside. In most cases, the less you’re prepared to invest in a partnership, the less valuable that union will ultimately be. Monogamy is a tough call and represents a choice, rather than a state we are naturally programmed for. It takes enormous sacrifice and commitment to choose a partner and stick with them, and the odds are heavily stacked against success. So the looser connection you advocate is perhaps more realistic. I’m just not sure how you negotiate the needs of individuals where both parties are only committed to pleasing themselves.

You clearly want more from the partnership than your boyfriend is prepared to offer and I’m sure the best advice is for you to move on and find someone who’s prepared to offer the minimal level of commitment you require. It’s very hard to abandon hope and act on the cold facts, so you’ll no doubt linger longer and make further excuses for his behaviour based on your forensic study of his psyche. The painful truth is he’s not available to you in the way you want and quite frankly deserve. If you act on my advice you’ll tell him that your bottom line is a much greater degree of emotional engagement than he’s prepared for. You’ll save yourself a lot of time and hardship by doing so but I fear just as he is determined to pursue his own path, you’re committed to making him see the wisdom of yours. I wish I could promise you any degree of success with that.

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