The character of the 'romance hero' in these books is a direct evolution of the Disney prince. He's often brooding, deeply traumatized, possessive but protective, and powerful in a supernatural or societal way. He's the Beast, the Beast, the Beast, and Hades, all rolled into one. While the heroines have gained agency, the male love interest has become a fantasy of intense, focused devotion and redemption-through-love.
It's interesting to track the lineage from Prince Charming (a bland plot device) to the Renaissance princes (slightly more personality) to the modern Disney hero (more flawed, like Flynn Rider) to these novel heroes, who are often full-blown antiheroes. It reflects a changing fantasy: from wanting a perfect, charming savior to wanting a complex, damaged partner you can heal and who, in turn, challenges and worships you. It's a power fantasy as much as a romantic one.