Dear Mariella

THE DILEMMA My 10-year-old son's father moved to Australia in 2007; before that he was mostly consistent with visits and contact. After his move he maintained contact with weekly phone calls, but these are now sporadic. Last year he stopped contributing to maintenance. His excuses varied, from losing his job to not being paid money he was owed. I was forced to go through the courts to establish a maintenance order but was unsuccessful, as he is not on my son's birth certificate and we were not married.

My question is: how can I permit him to keep in contact with my son when he has excused himself from all legal and moral responsibility towards him? I am angry that he has treated my son with disrespect and I'd have no hesitation in cutting him out of our lives. However, although my son is under no illusions about his father, he still likes to hear from him and I am concerned that if I prevent contact my son might develop negative feelings about himself. Plus, his family has kept in touch with us and my son visits them a few times a year, which he loves.

MARIELLA REPLIES The devil, as they say, is often in the detail. I'm curious as to why you didn't register the father on your boy's birth certificate. Was it a simple omission, a premonition of what his future role would be, or a way of distancing him, even at that early stage, from a shared role as responsible parent? Our behaviour speaks volumes about what we're really thinking.

I say this because I'm wondering if at some stage, very early on, you decided that you wanted this baby in your sole control, and your subsequent actions have increased the likelihood of that outcome. If you make people feel surplus to requirements, that's often what they become. Naturally, most decent folk would put up a fight for equal access to their child, but sadly for your son your ex-partner failed to enter the fray. It must be heartbreaking for your boy to experience that rejection.

No child escapes the scars of an irresponsible or unavailable parent, even if the other responsible adult goes out of their way to compensate for the absence. Imagining yourself surplus to your parents' requirements is horribly debilitating and can lead to many confidence issues in later life. I'm not blaming you, not least because I don't have enough information at my fingertips. But for this man to feel that he can disconnect from his son to such an extreme extent suggests he never properly attached. Why would that be?

Most likely he's one of those immature adults who refuses to take responsibility for their own lives or those to whom they cause damage. On the other hand it could be that you've made it easy for him to abdicate his duties and now you're experiencing the repercussions. In terms of a long-term resolution, it may be worth ruminating on that one at your leisure.

Plenty of parents do nothing to earn the love of their children and receive it nonetheless, which can seem terribly unfair if you're the one doing all the legwork. This man is a good example. Seemingly unplagued by any sense of personal responsibility, he deserves the contempt in which you hold him. Yet, of course, his son still loves him.

Nothing is to be gained by exposing your boy any further to his father's shortcomings. The more useless he considers his dad to be, the more damaged he'll be by the after-effects. He's already endured enough in shouldering his father's virtual desertion. As parents we take on a responsibility to protect our kids, and we can't be too selective about what we decide to protect them from. Illuminating your son further would also increase his anguish. Whatever you think of the man, your son needs him, and the more rewarding you can make that connection the better. When your boy becomes a man he will make his own judgment about what has happened between his parents.

Swallow your pride, anger and rightful sense of injustice, and for the sake of your little lad open up a Skype account. Step out of the equation and let them get on with it. That way if his dad is flaky he'll have to come to terms with it himself, rather than giving him cause to accuse you of negative indoctrination in later years.

You're absolutely right in maintaining the connection with his father's family. It will go partway to make up for his father's absence; it gives you, I imagine, an occasional much-needed break from sole parenting, and provides the sort of extended family that helps children to thrive.

You can afford to be generous – you have the most valuable asset from your relationship: your child. Remember, when it's murderously hard to swallow the injustice, that it's your son who sustains the real damage if relations are antagonistic between his parents. You clearly love him a lot, so make it your mission to protect him from those who can most injure him until he's old enough to understand the shortcomings of all human beings.

READER RESPONSES

A fortnight ago Mariella advised a 22-year-old fitness instructor who had fallen in love with his 46-year-old client. She only seems to want him for sex. Should he break up with her? Here are some readers's webposts:

This woman is just divorced so she is probably hurt and maybe hasn't much confidence. Be brave and tell her how you feel and ask her what she feels about you. HOSHINOSAKURA

The only positive quality you mention is that she is beautiful. Otherwise she seems thoroughly unpleasant. Ditch her. POLLYSTYRENE

I got used for sex once. It was brilliant. Seriously though mate, if you're really not happy, stop seeing her. In short, leg it. FOOTBALLDAVE

If you have a dilemma, send a brief email to mariella.frostrup@observer.co.uk. To have your say on this week's column, go to theguardian.com/dearmariella