That's partly because you're attracted to a cartoon. A star's media image is very carefully crafted. People like that are much less impressive in person.
And that's partly because Lazare is right. You can be eternally attracted to a media image because there's a broken feedback loop. If you were displaying your attraction to an actual person, you'd be getting either positive or negative feedback. Eventually things would either heat up or cool down.
Think about all the people you know that you once felt strong sexual attraction for. How many of them do you still feel that way about? For me, the percentage is tiny.
Also: continuing to display attraction signals to somebody who isn't interested in you? That comes across as creepy. As would fantasizing about someone you know who doesn't find you attractive. For your sake, I hope they don't find out.
If the author's black-and-white statement still is bothering you, go ahead and insert some nuance. E.g., "normally" or "for non-creepy people".