Rise of the Eromancer - Chapter 246 - : ...Huh?

Having lived a normal life all his life and died without being able to fulfill his desire and when he’s given a task by a god, watch how he takes the protagonists girls while making it hard for the hero.

Lin En transmigrated into a magical world that resembled medieval Europe but had the power of magic.Here, magic could affect and control basic particles, which was based on scientific theories that served as magic formulas!The wizards, who were actually scientists, were struggling to explore the truth of the world under the chase and blockade of the church. Lin En’s arrival sparked a renaissance of the alternate world…The white phosphorus fire, known as the Flame of Hell, the liquid nitrogen field of extreme cold, and the resonance frequency that kills without a trace… A few years later, the Holy See gathered all countries to the city, known as the legendary wizard, the pioneer of magic Lynn under the gaze of a group of wizards, wrote down the mass energy equation known as the ladder of God by later generations! Lynn looked around the crowd and said nonchalantly. “Mass and energy are interchangeable, and based on this theory, I have developed a powerful forbidden curse… It’s called — “The Big Nuke!”We will re-examine the world from the perspective of magic, where science is magic, and magic is science!

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

She was stupidly in love with him. Because of him, she became rude and unreasonable, overbearing, jealous, insane. But he did not spare a glance to her. Married for two years, he didn’t favor her once, letting her become the laughing stock of the whole world. Eventually, she ended up in an affair, leading to her tragic death.