Giving me Yona of the Dawn vibes... Lover/loved one betrays by MC by murder. Unlike Akatsuki no Yona though, this one focuses more on the emotional and psychological part with less of a physical plotline and gives us a reconciliation. Honestly, a tragedy if done well is addicting. You can't get enough of the sadness and the pain. I've found that a lot of these sorts of mangas just feel more realistic than others.