I reincarnated as an elf .......and married the yandere villainess.

Dr. Killian spent his life mentoring unstable minds, until one of his patients killed him.His next life begins in a fantasy world he vaguely recognizes from the same patient’s ramblings about a novel Killian never bothered to pay attention to.Reborn as Atheline Sunblade, a high elf noble from a family second only to the throne, Killian discovers his original role in the story was insignificant: he was simply the man sent to capture the villainess runaway fiancée.Determined to avoid the plot entirely, Killian plans to live quietly.Unfortunately, fate seems to have a twisted sense of humour.Instead, he casually befriends what he assumes is a normal dark elf soldier visiting the elven kingdom.She’s intense, strangely curious about him, and appears far too often for his liking , but Killian doesn’t think much of it after all. Every Dark elf he heard of was pushy to begin with.Until a cultural misunderstanding and several extremely unfortunate assumptions lead to one catastrophic realization.The “soldier” he’s been talking to… is actually the Dark Elf Queen.And somehow, he accidentally proposes.To make matters even more fucked up, he got a system that basically gives him useless things......It will have smut scenes and I will mark them for those who don't want to read them.