I see where you're coming from. I agree, I don't see how anyone can say they've 'fallen in love' with a character and genuinely mean it, but then, it's never really happened to me. I've thought a character is incredibly awesomeand obsessed but never romantically was interested.
Usually people who say they've 'fallen in love' with a character can just mean they like them and are being a bit overdramatic about it.
However, on the other hand, I can say that it's not scientifically impossible.
What I don't understand is how can you lovea cahracter that doesn't interact with YOU? If you fall in love with a character from a dating game because it seems you're talking directly to them and vice versa, it's different.
I mean, I fell in love with my boyfriend and I haven't even physically met him. Shouldn't that be scientifically impossible? I fell for his personality, I fell for him without images, not with words, but the feeling I got behind those words. The sense of 'someone'. I was in love with him before I even knew what he looked like, sounded like... all that jazz. I think I even knew the minute me and him met. I just had a 'feeling'.
On the whole "smell" thing... I think love runs deeper than that.
Like I said, I truly love my boyfriend. I really do. I know that that word is thrown around and I didn't realise how much until it actually happens to you. I realise that love can change when we meet, but that doesn't matter, I love him now. Not any fantasy of him, not anything he isn't or anything I'm pretending he is, but him.
.... However, responding to that theory, when I eventually did get something with his smell (his tee) ....lord... he smells so good...
No one else can see it, but I just think he smells so comforting and homely and I wann curl up in his smell... So, I can sort of understand that theory too.
Sometimes "love" or similar feelings just happen(s). So in that sense... I can sort of understand how different types of love exist, at a stretch even weird ones like falling in love with a 2D character. :/ Though that doesn't mean I agree with it and it totally freaks me out when someone pretends to be said characters' love interest, i.e. from the show they're in but there we go.