At its simplest, its the shield and filter effect. You are both protected by the magical wall of the internet and thus you get comfortable. He filters information to her and she to him. In essence in these three weeks neither probably knows who the other really is. However they have at least constructed desirable constructs of themselves for the other. He seems to have done more so than her in that she doesn't know much about him yet seems so drawn to him. He's pulled her in and she wants to know more because she likes what little she does know and hopes the rest will be to her enjoyment. Simply put, if you want to stop it, break her confidence in the construct. Find the smallest flaw in his logic, patterns, or information then exploit it, eventually the rest will begin to crack as well. If you want to give it a shot, make it a very public place, a place where he has no chance of whisking her or you away, stunning you, etc. I'd say bring someone with you who will watch from a distance. Make sure you tell her every single horror story you can find of kidnappings, beatings, rapes, etc at the hands of online predators to make sure she's actually prepared for the concept of meeting an internet person and the very real repercussions of such a meeting going awry and that she needs to recognize it and leave instantly. If she's 16 even though the legal age in canada is 14 in most parts I'm pretty sure its higher in Ontario isn't it? He's likely a guy who either can't or doesn't really try to get women his own age and thus looks to younger women, in any case something is quite wrong. I mean it could all be wrong, he could be a sweet caring guy who cares for her for who she is, but he'd be willing to wait and sort things out properly if that were the case.