After I Transmigrated Into a Book, I Discovered the Male Supporting Character Was Reborn

There are three latitudes of world space, In the first world, the original male and female protagonists like each other, the male protagonist likes the original female protagonist, and the female protagonist likes the original male protagonist. This is the original direction of the novel. In the second world, the female protagonist comes and falls in love with the male protagonist. The male protagonist still likes the original female protagonist first, and then falls in love with the female protagonist. The female protagonist finally dies on the way to get married. In the third world, the male protagonist is reborn and chases his wife. The female protagonist thinks she is in the second world.

Come on, the plot is okay, but it feels like it should be over soon

So why did the female protagonist die in her previous life and why did the male protagonist regret it??