Valkyrie Smash - Chapter 21 Bad Timing.

Infernal Demon Dragon: A dog like you dare to face me in combat? Do you wish to die so much?

A good-for-nothing man married a beautiful girl but was kicked off the bed on the wedding night. Furiously, he wrote a bill of divorce and ran away.
He was schemed a car accident in which he nearly lost his life. However, it turned out to be a blessing. He swallowed the soul that passed through the outer world, thus obtained superb medical skills and martial arts.
Later on, with the silver needles and invincible martial arts, he embarked on the road of counterattacks and was committed to his great dreams.

- Description from Novelupdates

Usami is a beautiful classmate with good morals and top grades. At school, she views Sakuto as her rival. But when he bumps into her after school, he sees a different side of her. She was playing at an arcade after classes, and she had this innocent smile that one couldn’t imagine on her at school.For the sake of getting along with her, he gets close to her at school and then plays together with her after school. They each have their places where they can deepen their bonds, and at last…This is the start of a heart-warming love triangle romcom!

Su Wan is a Realm Destroyer. She shuttles to different time-spaces using the identity of the “Cannon Fodder Ex-Girlfriend”, dedicated to plotting how to happily tear apart the male protagonist and the female protagonist. –There’s no such thing as protagonists who can’t be torn apart, only Ex-Girlfriends who don’t work hard enough~