What Happens When the Second Male Lead Powers Up

I was reincarnated into a romance fantasy webnovel that my younger sibling was reading, not even as the main male lead, but as the sub male lead. If my memory serves me right, this guy goes off to war later and dies in the main male lead's place. I've made up my mind. I won't go anywhere near the main characters, I'll stay healthy, and I'll return home. You two can have the romance all to yourselves! I'm just borrowing a little bit of the fantasy, okay?