I want their marriage to have been arranged since they were babies but they've never met or spoken to each other (look at it as one of those old-school Chinese weddings where the first time they lay eyes on each other is on the wedding night).

Meanwhile, unbeknownst to them, they've started an illicit romance with each other on the side and have no idea that the person they're in love with is actually the person they're supposed to marry. They talk about running off together, but the pains of duty to their countries/families/whatever keeps them from doing it, even though they're stupid in love.

And then, you know, the wedding happens.