At first glance two recent stories about under-age girls seem so different as to be incomparable.

One, that of Megan Stammers, the 15-year-old schoolgirl who fled to France with her 30-year-old maths teacher, Jeremy Forrest, has been the media frenzy of the week, mostly presented as a tale of lovers on the run, punctuated with the odd howl of outrage at the idea a teacher should so abuse his position of responsibility. The police search ended on Friday in Bordeaux, with her found "safe and well" and his arrest.

This couple have filled so many newspaper pages that they are fast becoming celebrities of a sort. Tweet by tweet, we have been delivered the back story of their romance. And throughout this steady deluge a debate has intensified, one that touches on a sensitive but – for some – rather grey area: that of how much freedom and how much protection we owe our girls and young women.

Last week, as it happens, also saw the publication of the report by Rochdale Borough Safeguarding Children Board into the way social services and police handled the scandal that ended in nine men being convicted of grooming girls as young as 13. This, of course, is an altogether more horrifying saga. There is no glamour here, no possibility of interpreting any of this systematic exploitation of young white girls by a group of mostly Pakistani Muslim men as grand romance; even if, in the recently published letters of one of the victims, the word "love" is sometimes used.

But, notably, these two stories do share something. In both cases there were institutions and individuals. They knew and yet did little or at least not enough, and too slowly. From the Rochdale report we learn the police and social services "missed opportunities". Allegations were not taken seriously. One of the girl's parents was told their child was simply hanging out with a bad crowd.

With Megan, we read that the affair had been going on and known of for some time, and that – seven months ago – the couple were seen holding hands on a plane flying back from a Los Angeles school trip. We see the tweets, we read the quotes from her school friends, we learn that the police had confiscated mobile phones and that Forrest had been told he was due to be suspended from his job days before their departure.

Megan's motto, we discover, was "YOLO" – "you only live once". Before they left she wrote on a social networking site that she was "excited, because I know what is to come". Forrest had changed his relationship status on Facebook from "married" to "in a relationship". We learn all this and we wonder why something more concrete had not been done to prevent it getting this far. Though, in terms of inertia, this is no Rochdale.

However, it also emerges that Megan's school, Bishop Bell Church of England in Eastbourne, has a history of being slow to deal with sexual scandal. In 2009, a teacher from the school was jailed for grooming pupils, and in March it surfaced that a retired priest, Canon Gordon Rideout, had been allowed to remain as a governor despite child-sex allegations against him. This leads to the impression of a culture of toleration, or at least of turning a blind eye to some of the signs of such behaviour. Here is an individual institution, if not an education system, in which staff-pupil relationships are not so fiercely mitigated against as we might wish.

But the real question is why that should be so. And why should it be that police and social services in Rochdale managed, for so long, not to take seriously the complaints? Cultural sensitivities about race have often – and rightly so – been blamed for the failure to protect the Rochdale girls. However, there is another issue that stands out in the report. It is that girls, aged between 13 and 16, were treated like consenting young adults by the institutions that should have protected them. Case files show social services staff often considered such young people to be "making their own choices" and "engaging in consensual sexual activity". This is almost as shocking as the abuse itself.

And it is not just social services that have this attitude – it is culturally widespread. Writer Peter Oborne, appearing on the televised debate show Question Time at the time of the Rochdale trial in May, commented that the victims had "accepted the advances" of the men. He asked, "What does it tell us about what's happened to our society that we have 12-year-old girls, 13-year-old girls, who are happy to give up their affection and their beauty to men in exchange for a packet of crisps?"

In other words, there is a prevalent conviction that young girls are somehow asking for whatever they get as soon as they begin to behave in a sexual manner, or choose to involve themselves with men. This kind of thinking is the sort that has prompted many women, globally, over the last few years, to march in SlutWalks.

The SlutWalk movement started because a Canadian police officer suggested that "women should avoid dressing like sluts in order not to be victimised". The belief that an underage girl is "making choices" when she gets involved in "prostitution" (as the abuse the Rochdale girls experienced was sometimes called) comes, surely, from a similarly misogynistic worldview.

It is no wonder, therefore, that there is such a growing young feminist movement. The girls of today are, after all, poised between a rock and a hard place – brought up in a culture in which sexual allure is a defining attribute of womanhood, and yet when they develop it they are accused of simply "asking for it".

Though Megan's elopement may seem a minor societal worry compared with Rochdale, it suggests a similar attitude – one in which people just let the kids, and the adults, get on with it. Forrest may seem to be a gentle type. One could say (and many do), "They're just in love – Let them be". But we can't afford, particularly in this era of so-called "early sexualisation", to let go of the notion that the legal age of consent is to be respected and that the pursuit of sexual activity with those under 16, by those older and with responsibility towards them, is criminal.

Even Megan Stammers, with all her exuberant passion, is a reminder of why we consider young women of this age still vulnerable, and still children.

Hers may be a great love story. But that word love, and all the romance we attribute to it, is not enough excuse for turning a blind eye. Love lurks, in some twisted form, behind many a story of abuse. And Rochdale is proof of that.