Okay, so this is my absolute jam. The core conflict? It's never really about fangs or scales, is it? It's about fundamental misunderstanding. Humans see a threat, monsters see a territorial reaction. Like, in 'Strange Love' by Ann Aguirre, the alien Zylar is horrified by human 'softness' and finds our emotional displays illogical—that's a huge cultural chasm to bridge before any romance can even start.
But then you get the darker side, where the monster's very nature is a danger, and the human has to decide if that's a deal-breaker. A lot of shifter romance plays with the fear of losing control, of the beast hurting the one it loves. That internal monster vs. human conflict within the same character gets mirrored in the relationship. Honestly, I think the most compelling stories use the monster aspect to explore real-world issues of prejudice, fear of the 'other,' and what we're willing to accept for love.
It always comes back to a question of consent and autonomy, too. Can a being driven by instinct truly choose? That tension is everything.