Crow doesn't understand how fault works. The prince and mistress only made the situation worse. Einz didn't need to be secretly meeting a married woman (As far as he knew) and he really didn't need to be going whilst poisoned. He was too down bad and caused the whole thing. Not saying it was a bad thing in the end for the mc but seeing the author trying to make pity for the character is gross.
Also Einz coming back to finish what he couldn't start is cringe. Getting in the perfect place right next to her in the aftermath. That's just fuc*** up IMO