Romance novels often have antagonists who create obstacles for the protagonists, but they aren't always villains in the traditional sense. Sometimes, it's a person like the overbearing mother in 'Pride and Prejudice', Lady Catherine de Bourgh, who tries to prevent Elizabeth and Darcy from being together. Other times, it's societal expectations, like in 'Jane Eyre', where Rochester's secret wife acts as a barrier to his happiness with Jane.
In modern romances, the antagonist can be a ex-lover or a rival, like in 'The Hating Game', where Lucy's workplace rival Joshua initially seems like the enemy but ends up being the love interest. Even internal conflicts, like personal fears or past traumas, can serve as antagonists, such as in 'It Ends with Us', where the protagonist's struggle with her abusive relationship takes center stage. The beauty of romance novels is that the antagonist isn't always a person—it's often the circumstances that make love seem impossible.