The dilemma My ex broke up with me at the start of the summer. A week later he wanted me back and expected me to jump at the offer and so began a long summer of him emotionally abusing me. We eventually stopped talking altogether but, after a while, I reached out as I wanted him back in my life. I arranged to see him and I told him everything that was going on in my head. He ended up kissing me which I did not expect. We had such a good day, everything felt natural and I was so happy. He came back to mine and kissed me again – he was initiating everything.

He then left mine and went to the pub where he got with someone else. He posted on Instagram a pic of the two of them together and has still said nothing to me, three days later. He left me on such a high, thinking we could be getting back together. I haven’t been able to sleep. I’m going crazy. It’s destroyed me. I want to scream and shout at him, but I also have nothing to say. He clearly doesn’t care about my feelings. What do I do?

Mariella replies You know the answer, don’t you? There’s no way you can have typed out that letter to me, forcing you to dwell on recent events, and not realise that there’s absolutely nothing about this man that’s worth clinging on to. Clearly there’s a physical attraction, but if he remains the puppet master, plucking away at your emotional strings without a care for your wellbeing, there’s zero chance of ever achieving happiness together.

It’s startling how quick we are to condemn the behaviour of others – but even swifter to forgive the trespasses of those we’ve linked our emotional fortunes to. Even after describing his behaviour as emotional abuse you still can’t give up on him. What is it you are hoping for? Happy ever after? Total change of character? Contrition for his selfishness and betrayal?

Mooning around over a guy who isn’t worth it is simply not OK

The truth is we’re all fools for love because our insecurities shout so much louder than rational thought when it comes to matters of the heart. If someone treats us badly, the easiest thing in the world is to allow their behaviour to merely confirm our own poor opinion of ourselves. You won’t be the first or last person to make excuses for a lover who has brought you down so low you believe it’s your destiny to survive on scraps of affection. But it’s not good enough to act like a bystander in your own romantic life, mentally or physically.

Expressing surprise about this guy kissing you is offloading responsibility for your own complicity. You’re right that his interest in you is natural, but whether he’s a loyal, respectful and reliable man is entirely different. If you’re not prepared to make your needs clear and stand by your principles, you leave scope for philandering fools like him to break through your defences.

In this instance I’m afraid you’ve netted a big fish. You’re not going crazy – you’ve been treated badly by someone whose sole focus is his own immediate gratification, which is bound to cause sleepless nights and emotional agony. That’s hardly the foundation you want to build a relationship on or the sort of guy you want to “hitch your wagon to”, as the saying goes. So I hope you haven’t written to me in the hope that I’ll dissect his recent behaviour and come up with plausible excuses for why he would carry on thus. We both know that the answer is simply because he can.

What you may have lost sight of is how much easier life becomes when you take charge of your destiny and make your own choices. I took my teenage daughter to the Frida Kahlo exhibition at the Victoria and Albert Museum the other day and it inspired me to rewatch the biopic Frida. It was interesting to see how a movie released 17 years ago could have dated so dramatically. Here was a portrait of a turbulent love affair – the dysfunctional coupling of Kahlo with her husband, the Mexican megastar artist and seducer extraordinaire Diego Rivera.

Through her art her pain was writ large, not just because of her near fatal accident and subsequent disability, but because she’d hitched a ride with a man who was passionate about her, but loved himself more. When I first watched the movie I was captivated by the charismatic and corpulent Rivera and moved by the tragedy of his insatiable weakness for female flesh. Watching it again with my daughter I felt my reaction then – to accept that such a man needed to sate his desires – had been primitive. In the film, equality between them was illustrated by Kahlo embarking on the odd liaison of her own, proving she could do likewise. My daughter was not similarly understanding and kept asking, why did Kahlo put up with that big, fat, lascivious fool? I didn’t have an answer.

Our world is no longer ruled by power-abusing men and their desires are no longer what we shape our lives around. In this landscape, mooning around over a guy who isn’t worth an hour of your thoughts, let alone three sleepless nights, is simply not OK. There are billions of better men to choose from on our overcrowded planet, so you don’t have any excuse for settling for less than you deserve.

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