The best action-fantasy with a strong romance element I can think of is InuYasha and its sequel, InuYasha: The Final Act. It's set in a fantasy version of medieval Japan filled with demons and monsters, but there is a strong romantic element to it that keeps it from being yet another superpowered action series for boys.
You can find it on SideReel at http://www.sidereel.com/InuYasha - it's all streaming online. It's based on Hulu, though, so you can't see it unless you're in America.
If that doesn't work for you, you can also try shows that focus more on the romance than the adventure, like Fushigi Yuugi.