I'm looking for a novel (KR, JP, RRL) or manga/manwha/VN where the ex-love interest regrets their decision of abandoning/betraying/turning away from the MC. IMPORTANT: I want the regret NOT to be because they realize or desire the MC's success/power after "proving them wrong." I want them to regret because they realized they took what they had for granted, that the MC did truly love or care for them but they were blind and tossed it aside, that they discarded true love for something not even worth it, that they now are missing something, that what they got in the end can't compare, that they too were/are in love with the MC, etc. A novel that illustrates pretty well what I'm looking for is "The Girls Who Traumatized Me Are Glancing at Me, but I’m Afraid It’s Too Late" or "Ryuu Kusari no Ori -Kokoro no Uchi no “Kokoro”. I just enjoy watching kind-hearted characters realizing that they fucked up and being ravaged by the guilt.
Coiling Dragon Not a romance novel, but it has a bit of it in it and it also has what you described in it.
Thanks for the rec but I would rather it be one of the main plot points rather than just a bit, especially for a novel with 800+ chapters.
The Only Thing That Reached Out to Me, Who Was Broken, Was Your Hand I'd say this is the most similar to The Girls Who Traumatized Me. MC got fucked over by girls and is broken because of it, now they're wallowing in regret and squirming for his forgiveness. And like Girls Who Traumatized Me, Spoiler: spoiler from the raws this one features parents with their incompetence driving the MC into a corner, and now the MC left the household and disassociated himself from his family, which they whine and cried about lol
One of the stories where i reaaally remember such ex gf regrets was from Martial World, the author never lets go off a chance to show her regrets throughout most of the novel considering everything happen within the first hundred chapters