She loses her whole family and loses the love of life a year or so after the manga ends.

The manga implies that his mother died giving birth to him, and not only that, he was born a hermaphrodite and was totally rejected by his father and, later, step-mother, who hadn't even the grace to give him the name, leaving him with "Sora" the name his mother had intended to give him if he was a girl. His parents finally lost it enough to try to kill Yoite, but only succeeded in slashing his neck open so that he had time to run and collapse outside of his home, and have the utter misfortune of not dying, and instead being picked up by a man cruel enough to use a boy who had no will to live to make him learn a forbidden technique that strips away your senses and ruins your body the more you use it. So enter Yoite at the beginning of the story, a 16-year-old matchless killer for whom death is imminent from over-using the Kira technique. GOSH.

It doesn't help that the author makes you feel Yuca's pain and confusion and bitter near-insanity. So he's a child who is reborn every time he dies. He's technically immortal, but doesn't even have he advantage of an immortal body, and he is not even guaranteed immediate reincarnation, so he's lived thousands of lives, to the point where he remembers each one, not completely, but enough so that life is little more than a transient dream where you wake cruelly into a new one each time you open your eyes, and everything you love is gone each time. Over and over again until reality isn't real. Yeah, I'd lose it, too.

His life was pretty good for a while. Born into a high-ranking family of Vampire Hunters with a twin brother he adored, his most pressing problem was a huge amount of guilt that he was in perfect health while his brother was perpetually sickly, due to the fact that twins of Vampire Hunters are cursed to devour each other in the womb. Pretty bad, but not Angsty Bishie of the Month material. Yet. But then his parents were contracted to kill the ex-human lover of a pureblood, who was supposedly on the brink of insanity, which is inevitable for all ex-humans, and said pureblood struck back, killing Zero's parents, biting Zero, and taking his twin brother, who claimed to have resented Zero and his parents for his entire life. To top it off, Zero spent the next four years resisting the transformation to a vampire and the inevitable descent to Level E, when he will become violently insane, and also falling in love with a girl who is infatuated with a pureblood vampire that Zero loathes. And that's really only the beginning.

The series speaks for itself. There is absolutely no one who does not need hugs and counseling in that entire series.

His family was killed before his eys from a girl he likes. mybe he deserve it a little becuse he has lied but still...

He killed his own wife without the intention to do so