Look, i get the whole romantic side of blood relationships, i fawn over it as well, there's nothing inherently wrong with it, however if it's something that comes at the cost of someone, someone you claim to love, someone who needs you, then it's not romantic at all, it turns hypocritical and narcissistic.
Family are ultimately those who will never abandon you when you need them the most. I understand he may have felt betrayed, but if he ever considered how she felt, if he ever considered her to be family, that was the moment, where he should've at the very least listened to her side, and tried to understand what she had to say.
Family are people who love, who listen, and then throw hands but ultimately comes back together again, the deep bonds between a real family is not something that can be broken on a whin, whoever she looks like, or whatever invisible DNA match she has, it shouldn't matter, not over love, ever.
Anna my dear, forgiveness is something altruistic and admirable, i will never shame you if you choose to go down that route, however no one deserves to be treated they way you have, much less from someone you hold so dear, you're deserving of so much, so keep that in your heart and don't forgive him out of duty, do it only if it is what you truly want.
I don't know what kind of world you live in, but unless dystopian, there will always be people who can love you for who you are, and it's not something that can be bought, relationships are not jobs, whether you're "talentless" or not, you don't need to prove yourself worthy of being by someone's side.
MY HEAR- MY HEEEAAAARRTT--- DON'T DO THIS TO ME!!!! THIS IS SO CRUEL! (Not beacuse of spoilers) I KNEW THEIR RELATIONSHIP WASN'T GOING TO LAST, BUT THIS IS TOO EARLY!! AND IT'S SAD. And i KNOW, it's gonna BREAK MY HEART FURTHER. NO. NO NO. no. No. no... No <3. I hate myself, i hate this manhwa, i hate the world. Author-nim come here, i'm about to get real silly aha~! Fuck, fuck, fuck, fuck, fuck, fu
I need my soul to be cleansed after reading this.