Why Did a Romance Novel Give Me a Monster-Fighting System?

[Half female-oriented + one female lead (Ye Xuetong) + plot-focused + not a wish-fulfillment story + no monster-grinding power-ups] My name is Lu Chen. I transmigrated into the world of a melodramatic romance novel and became the second male lead, a lovesick simp I hated most. The male lead, Xiao Mo, threatened me, demanding that I leave the female lead, Gu Suyan, and offered me a huge sum of money. I agreed without a second thought! Compared with the aloof female lead, the supporting female character Ye Xuetong, who quietly gives everything, is definitely more appealing! It's just a little strange. Isn't this supposed to be a romance novel? Why is my golden finger a monster-hunting System? My name is Gu Suyan. In my previous life, I was moved by Xiao Mo's relentless pursuit and eventually married him. Then I died... The one who killed me was Xiao Mo, the man who shared my bed. I was such a fool. I didn't realize until I was dying that Lu Chen was the only one who would never betray me. Fortunately, Heaven gave me another chance and let me be reborn one year in the past. “Wait! Why did Lu Chen break up with me of his own accord? That's not how it happened in my previous life!” “Can someone tell me what on earth is going on?”