In this story, Lessa, a young woman with the ability to telepathically bond with dragons, falls in love with a powerful bronze dragon named Ramoth. While Ramoth doesn't actually turn into a human, he can take on a more human-like form, allowing for closer physical contact and companionship. This is a key aspect of their relationship.
There are other fantasy novels with similar themes, but "Dragonflight" is the most prominent and widely known. If you're interested in exploring other options, perhaps providing more details about the story or characters could help identify the specific novel you're looking for.