Imagine Person A of your OTP being an assassin, and they are told by their boss to kill Person B of your OTP. Right before A kills B, A tells B that they love them. After B is killed, A kills themself out of grief.

Assassin
Imagine Person A of your OTP being an assassin, and they are told by their boss to kill Person B of your OTP. Right before A kills B, A tells B that they love them. After B is killed, A kills themself out of grief.