I think the Japanese video game dating thing is quite interesting, or sweet, even if a little obsessive. People always have relationships with inanimate objects or documents (and a computer program on a game boy cartridge is a document, to be sure). If you're looking at it all from space, I don't think it makes a lick of difference whether a person is going on vacation with a real girlfriend or a fake one. Would it be any weirder if you loved the work of Charles Dickens, or the Beatles, and went on vacations with their albums or books, doing the things that they do in those texts, reading them or listening to the music along the way? I suppose you could say someone who does that is equally whacked. But I feel sympathetic, I guess. Do you?
Maybe the reason that this seems weird is that Love Plus+ isn't part of any sort of canon. Or maybe it goes deeper than that. Maybe because the game is more interactive, it is closer to simulating some kind of totally demented and simplified aspects of human interaction, and so it seems that these people are perverted or deluded monsters of some kind.