Write a fantasy novel.  NAME_1 is a shy 29 year old man has a secret.  He is a vampire but he has never tasted human blood.  He is a shy gentle introvert man and does not know how to approach his blood donors.  But he has to drink his first human blood before he turns 30 or he will vanish forever. Y is his human colleague and he doesn't know NAME_1 is a vampire  and he is secretly in love with NAME_1. Shy NAME_1 is not aware of Y's feeling toward them. Y notice that NAME_1 is not very well these days and he wants to help NAME_1. But how?  NAME_1 does not know whether it is true or not but the legend among the vampires  says that vampires should not drink the blood of someone who are in love with them or they will live in agony and despair forever. The legend is true in some way, the  agony and despair for the vampires means they lose immortality and must live as ordinary, mortal humans.