Writers can reverse the theme of "Romeo and Juliet" to create a different kind of romance. Instead of the families fighting, the romantic interests could dislike each other intensely. The story could involve them being forced together so that they have to get to know one another and falling in love despite having fought for so long.
For example, perhaps two feuding families decide to end the feud with a marriage by marrying one family's most eligible daughter to the other family's most eligible son. The married couple does not agree with the peace between the families and does nothing but fight at first. One complication would be if the two people have never met before, as in an arranged marriage. Eventually the conflict between the husband and wife is resolved as they fall in love. Perhaps the woman becomes pregnant or one of them gets seriously injured. Perhaps the marriage doesn't resolve the families' feud after all, but despite that the husband and wife resolve their differences.
Magic often makes stories more interesting, especially when it comes with rules and riddles. One such approach to a romance could be for the couple to have unusual beginnings. Possibly they are two different species or one is secretly magical and involves the other partner in a magical adventure. Perhaps the two have to surmount obstacles such as solving riddles that end in curses or death for the wrong answer or finding magical items that will help them change their physical form or gain release from a curse. The partners fall in love thanks to shared adversity.
A story could begin with a young man with a pet cat that routinely scares away his potential romantic partners with her wild and vicious behavior. She is, however, very loving and sweet toward her owner. The writer should work into the story, subtly, that the cat disappears at certain times---perhaps the hour of sunset, perhaps during the full, half or new moon or maybe when a certain constellation is in the sky. In any case, the owner should discover that his cat is a human in cat form and begin a journey to turn her human again. By the end of the story the couple should be quite in love, though the young man will feel reluctant to admit it. The ending is up to the writer; love can turn her human or something else may. The ending may also be sad with the woman remaining a cat.
This type of romance involves two people in love who fail to recognize it throughout the story. Their friends and family may see it, even complete strangers may see it, but the two protagonists simply remain oblivious. Complications can be introduced, such as a woman moving far away or disappearing mysteriously. In the midst of searching for her, her friend could finally realize the intensity of his affections. Possibly the woman is seriously ill or has experienced trauma. Perhaps her circumstances have led to pregnancy or a marriage that precludes a full romantic relationship with the man. While most romances end happily, that needn't always be the case.