He's too deep into the lie now. Don't bother trying to extract the truth, he'll take this one to the grave.
When I was a kid, parents would set us kids up on "play dates" although at that age we were way too young to even understand what love was, so it was never a worry.
But as a teen, especially one older than him, yeah, I had a feeling it was trolling. In his response there, he said his girlyfriend said he never mentioned love, (even though I'm sure we could find examples of it on the forums here) not even a few lines after he mutters "I wish" when the father confronts them about supposedly having love. (kinda makes me wonder what he'd have said if I hadn't said anything about it.) And uses a facebook pic of her probably without her permission (considering he even knows the person he randomly stalked for a picture) I could probably go on, but I'm bored with it now. Maybe later.