BL?
can be BL or Straight, do you have some?
Just re-read what you searching for. I'm not sure about cheating in marriage. But I have too many angsty story. So, If thats okay I'll gladly share.
Sure, I would love to see those angsty stories!
My favorite angst in this site is Ten Years Where I Loved You The Most —> https://www.mangago.zone/read-manga/10_years_where_i_loved_you_the_most/
If you want list, you can visit this; https://www.mangago.zone/home/mangalist/1299387/?filter=&page=1
If you interested in novel, (I find more pain in novel than any manga) my favorite is No One Saved Me —> https://www.novelupdates.com/series/no-one-saved-me/
I re-read this novel anytime I want to feel pain then cry river.
This novel list will give you scar:
https://www.novelupdates.com/viewlist/78661/
Some straight angst (novel):
Our Second Master (short read but wholesome); https://www.novelupdates.com/series/our-second-master/
Falling Dreams of Fang Hua (they both literally tormented just because loving each other); https://www.novelupdates.com/series/falling-dreams-of-fang-hua/
Im looking for angsty reads where the mc is married but the partner is cheating. Can be isekaid or normal settings.