Children don't have private rights as far as most people are concerned in most settled cultures.
The problem with minor-adult sexual activity is that the established rights of adults outweigh the distinct lack of rights that most children have, and if the relations are discovered by any of the child's guardians who feel that they were problematic, a very difficult situation transpires in which the guardians' views have to be enforced even if they are in conflict with the views of those directly involved in the relationship. The minor's views are trumped by the guardians', and the adult in question was responsible for subverting those guardians even if the condemnation of a potential relationship wasn't made expressly known (hence it's a law).
So even though relationships are things that just kind of happen based on feelings and circumstance, and the truth is that no one is practically to blame, there is almost always an awkward sequence of events that leaves everyone feeling betrayed and the pedo takes the fall.
I can accept that children below a certain developmental threshold where their parents inherently have control over most of their day-to-day lives are better off without private rights to select sexual partners.
But once children express an interest in sharing their sexuality with others and have the autonomy to do so with certain types of people it becomes a necessity for those rights to be granted or else we get problems like this one and similarly, although it's not technically criminal, my relationship with my niece. Even non-criminal pedos are going to create situations like that by simple virtue of existence. We cannot just say "pedos should not exist" obviously; and actually, we have an important role to play in society and a great deal to offer many kids and many families if the culture around sexuality were only more relaxed, and of course it becomes so with each new generation currently.
Under the present conditions we face an awful lot of injustice and an awful lot of children need to be indoctrinated to hate us (and usually, therefore, to hate sex) in order for the status quo to be upheld. It isn't the ideal way by any stretch of the imagination; if only more people had the cognitive capacity to see that the status quo constitutes a socially constructed taboo that ought to change just as much as the taboo around homosexuality was ought to change - and that, one way or another, we ultimately have no choice but to trend in a more sexually enlightened direction. And regardless of what form that enlightenment takes, it will constitute a societal relaxation around at least some aspects of pedophilia if not its eventual induction into culture as a complete "sexual orientation" in and of itself.
Those private rights to one's own bodily functions are innate, and those private rights to another's bodily functions (with their consent) should without any doubt be granted as soon as a person has the desire, the means, the freedom, and a chosen partner with which to engage.
That there is an actual large disparity between the age at which those conditions are met for most people (let alone the exceptions) and the age which those rights are legally granted (16!!!) is the crux.
Try as we might, it is practically impossible to socially engineer a change in timing of those conditions or to actually have a fixed at all. The alternative solution is creating a scapegoat. It may be despicable and even create a lot of (actually) abusive situations, but the sad truth is that as long as the general public has somebody to throw their blame at whenever something happens unexpectedly that conflicts with whatever they had planned, that's all they really care about at the end of the day.
So as far as I can see, we need to make friends with some reaaally chill parents, show them through demonstration how great we are with their daughters, and date them secretly until they are legally granted rights to private affairs. It's really our little girlfriends who make the change over time, so ideally we want to do everything we can to save them from indoctrination by the powerfully pedophobic media and preserve their faith in love and human nature.