Um, well...I guess Skyward Sword could be quite romance-heavy, but isn't it a bit too early to name it the most romantic? I think I'll stick with released games, thank you. =)
So, back to that. I have to decide between a few, actually.
I think Ocarina of Time is pretty romance heavy as it has some of the most popular pairings even though none of those really happened (other than fan-works, at least as far as I know
), which makes it romantic and not romantic at the same time. I think it's on a league of its own because of that, actually.
I always saw Minish Cap as somewhat romantic because of the beginning, but that was more like Link and Zelda being childhood friends....I guess. Malon was also in it, but I guess she doesn't count here.
Link's Awakening, from what I've heard of it, also has heavy hints of it. Sorry, but no spoilers from me. It's not like I've actually played it anyway. XD
Twilight Princess...I don't know. I never saw the LinkxIlia thing as fully fleshed out. But I guess it wasn't really supposed to be an in-your-face kind of thing.
You know...I find it funny that nobody's mentioned Spirit Tracks yet.
With that ending it had...seriously.
Then again, I'm not sure if everyone will agree with me on those. Remember, it's just my opinion.