The evolution of their feelings could be quite complex. They might struggle against the order at first, but as they face challenges together, a bond forms and turns into love. Alternatively, one might fall in love quickly while the other takes time to come around.
Their feelings might start as reluctant but gradually grow into love as they get to know each other better.
Well, it could go a few ways. Maybe they initially hate the idea but then discover hidden qualities in each other and fall deeply in love. Or, they might always have had a secret attraction that gets a chance to blossom under the king's order.