Despite what US law says, it's not valid worldwide therefore these arguments about law itself are ridiculous trying to oppose on everybody since not everybody lives there, you know. Even on moral grounds many seem to have their own inner moral code they go by (ahem, look at religion - all having their own) and oh my, if someone crosses this fine line; all hell breaks loose. But since we talk about law now, I'll say how things go here before I give this topic a final rest.
Here one police officer keeps his own blog and he is also actively pursuing bullies and other illegal activities on Facebook during office hours. He has written that from legal perspective 16 year old girl can have sex (yes sex, not just dating) with 50 year old man. Socially acceptable or not, it's still perfectly legal if nothing illegal is going on such as rape, using enticement tactics or others. There has also been discussions of lowering the 16 year limit to 15 here.
This topic has long ago went off the rails from what it was written. I leave the rest of your legal and personal level moral arguments for you to discuss between one another. In general, I recommend relaxing.