You also wrote:

If you suppose a child getting involved with an adult and imagine the consent is informed, it would seem most likely that the child would be the one to break things off as they grow and change.

I do not believe the last part of your sentence, and do not imagine that a child would be effectively "informed" regarding sex compared to an adult.

Notice the word "imagine" that I used. I did not say they could be adequately informed -- but my imagination was enough to entertain the idea. Given that counterfactual, I was speculating on what might follow. Adults do form non-sexual friendships with kids, and I think it is a common experience that the kids' interests are more likely to change than the adult's.