The dilemma My girlfriend of 18 months has said no to having another child. She’s 44, I’m 38 and she’s my first serious relationship. I’m completely broken; she has known from the start I’ve wanted one. She already has a six-year-old daughter from an abusive, cheating ex, who got her pregnant after six weeks together and left her just after their daughter was born. Her main reason seems to be medical complications from her first pregnancy. I haven’t really bonded much with her daughter – she adores her mum – but that’s probably her age. I feel unfulfilled in life, have an average social life and job so bringing up someone’s else’s child isn’t the same. I fear being alone again without the support she has given me – more than my own family would. I was thinking of surrogacy as a desperate last resort but that seems weird, and may only be viable if she didn’t have a daughter already.

Mariella replies First things first. This is the sort of non-negotiable detail that I wish budding couples would attempt to settle, or at the very least establish ground rules on, at the outset. There’s no other partnership we’d enter into without defining terms and the person we’re attempting to spend our lives with seems the most serious of any such prospective union. I appreciate that falling in love isn’t a rational matter but despite the rush of hormones to the head there are certain stumbling blocks that even blind love won’t overcome. Whether or not to have children would certainly seem to fall into that category. Perhaps your girlfriend failed to articulate her reluctance to have another child, or perhaps like so many others you didn’t stop to listen, or presumed time would shape your future together in your favour.

She seems pretty emphatic that she doesn’t want another child so I’m not sure what you want me to do about it. For better or for worse, we women are, among many other things, incubators. Rightly, that gives us final say on whether to procreate although it’s a powerful choice we far too often leave to chance or fate. Has it occurred to you that she already feels she has her hands full?

First of all there’s her six-year-old, with whom, by your own admission, you haven’t yet developed a meaningful relationship. That would definitely have been a good place to get in some practice on the parenting front and the first lesson to learn is that you need to work hard for any kid’s affection, whether biologically created or romantically inherited. How do you see that unrequited relationship panning out with a new baby in the house? It’s one of many serious considerations that you seem to have deftly dodged in place of your dogged determination to have a baby in your own image. Second, and perhaps most importantly, when you describe your relationship you could be describing a parent rather than a lover. The only regret you seem to have about the possibility of splitting up is that you will no longer have her exceptional “support”.

Career frustration and a desire for distraction are not great reasons for having a child. Too many children are already born out of carelessness or the misplaced notion that one small life will make up for one larger unfulfilled one. Your reasons for wanting a child appear to centre on a desire to improve the quality of your own life. As any parent will tell you, that’s initially unlikely to happen when you assume responsibility for a defenceless baby.

Creating a little mini-me that will add colour and excitement to your humdrum existence is a huge responsibility to place on the shoulders of a child and highlights your misplaced expectations of parenthood. It sounds like you have a lot of work to do on achieving contentment in your own life before you’re ready for a committed relationship, let alone bringing another human being into the world. Having placed the burden of “support” on to your girlfriend’s shoulders, you’re now looking to her to give your life meaning and purpose by bearing you a child, and that alone is a good enough reason for her to decline the invitation.

You chose a woman perilously close to the end of her fertile life, who already has a child and seems little interested in having another. If she expressed enthusiasm at the outset you have every reason to feel aggrieved. If this baby-daddy determination of yours is genuine – and not just a whim in pursuit of personal fulfilment – then the answer is an easy one: it’s time to sacrifice the security of this relationship to seek out a partner who is equally committed to starting a family.

I’m not convinced that you are prepared, or that you’ve realistically considered the consequences of – rather than romanticised ideals for – starting a family. That said you wouldn’t be the first person who walked blindly into parenting and learned about the skills and the sacrifices on the job. It looks like the right choice for you is the wrong one for your partner, which means it’s time for you both to start over.

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