"Loyal Dog" is right. That's way too flighty a person who is clearly as ditzy as she is popular to go hanging every hope and dream upon like he's doing.
I honestly do not see things working out for him, at least in the way he wants. Especially because any relationship he could get with her is predicated on him being more of a servant than someone of comparable level in their dynamic. Sure, chances are it'll end up with them together because he's the lens character and she's the protagonist and they're the first two characters introduced—but that's a lot of work to be done making it seem reasonable.
(Unless that bunny toy flashback is actually her having feelings for him first, and then thinking he didn't reciprocate which is why she ended up with his brother, and all of this is a misunderstanding or some nonsense. Which....not really compelling, so I hope that isn't the case.)
at any rate, this being a "slapstick rom-com" though means it'll likely just play his feelings for laughs while she gets up to whatever hijinx she does and he suffers in the background because he lost before ever getting into the game. It's a reverse harem story to boot, too, so I don't see another romantic interest being introduced for him to make her look his way or anything and push romantic development in that manner, either.
Plus, again—"loyal dog".