Help finding manhwa PLEASE

I remember reading this manhwa about a young girl who'd been through multiple lives, and was basically doomed to constant reincarnation every time she died. One of her lives was famous as a saintess because she was basically hypnotised by memories of her previous life into massacring everyone at the church. But she met a demon, as a child, in her current life, and they met again after he - having possessed a duke's body - conquered the nation she was from. They ended up in a mutually beneficial marriage, and he started 'consuming' her nightmares about past lives, because they were pretty much all traumatic in some way or another.

I cannot recall the title for the life of me. She's blonde, and he's got white hair in demon form, black in human, and uses they when referring to himself (as in multiple beings in one body. Not gender non-conforming). After the lists crashed, I can't seem to find it any more.