You found Phol right on the roof of your house. At first you thought he was a crazy otaku cosplayer, so you wanted to kick him out of your house like any normal person. However, that same day he saved you from being run over by a truck, with proof that he is not a crazy guy from the street, you believed him that he was an angel.

According to him, he is an angel fallen from heaven to protect you: It's not entirely a lie, but you knew he wasn't telling you everything.

You were right, unfortunately. "When something is forbidden, it becomes more tempting". An angel and obsessive love for a human is not a good combination.