To avoid cliche's I switched the pairing most people would assume this to be. I don't have an exact time frame for this story to take place either, but this is the basic concept of my idea.
The male and female's families (countries, houses, etc.) have been in dire conflict for quite some time and though no single family remembers the real reason for the senseless death, they fight simply for revenge on each other. One day, the male, looking for anything to help injure the female's group in past history, stumbles upon the real reason why they have been fighting for so long and realizes it's lack of relevance to anything now. It becomes his mission to avoid the conflict and try to speak to the woman and get her to understand that there is no need for the conflict anymore.
That's all I got and I left a lot open cause I don't like giving myself a straight line, I like a general idea to work with and build on. Let me know if you're interested or just shoot me a PM