Re:Zero Kara Hajimeru Isekai Seikatsu - Arc 1 – Chapter 15: Because He Is The Sword Saint

Witnessing her boyfriend cheating on her with her bestie, Shiyao was so angry that she went to a pub for fun and met a man, who was really a piece of work. After a crazy night she fled away, but was embarrassed to know that the man she slept with was her boss You Ze.
Jesus, give her a break!

- Description from Novelupdates

I became a side-character who died in anguish because of her good-for-nothing husband.

If I can’t avoid getting married, why don’t I change who I marry instead?

“Excellent, marriage sounds good.”

“Wise choice. Then let’s have a wedding ceremony that isn’t too ceremonious. Following that, I’ll need you to go down to the Fief and behave like the lady of the house until I call for you. Naturally, there won’t be any time to spend in leisure whilst dousing yourself in luxuries.”

“I’m not marrying you, but your father instead.”

“……Pardon?”

“I’m not going to marry you. Do you have a problem with that?”

“I thought I was dead, but when I opened my eyes, I found myself reincarnated in an abandoned RPG game. I intended to gather the heroes I had trained to form a guild once again, but…“I thought I was dead, but when I opened my eyes, I found myself reincarnated in an abandoned RPG game. I intended to gather the heroes I had trained to form a guild once again, but…Hmm… it seems all the heroes have completely lost their minds.”

I reincarnated and became the young sect master of a sect that dominates a region.I originally thought that with my solid backing, I will not have any worries in this life. However, sudden changes occurred and the sect declined.When the last ten disciples were forced to leave, only a deaf old man and a dog named 'Haha' remained in the sect, I suddenly discovered that the buildings in the sect could be upgraded!I'll upgrade the main hall!I'll upgrade my residence!I'll even upgrade my kitchen!A super sect is currently rising inexorably like the Sun...Welcome to my sect.I only accept disciples that are geniuses. Even super experts have to pay if they want to join.There's no free lunch in the world!