The three major misconceptions in life are: someone called me, I can pass this exam, and he likes me.
"Can I be your boyfriend?"
"You must be sick!"
"... Hmm"
Jiang Jiashi is really sick and will be cured.
If you don't know what love delusion is, look here.
Delusion of love is actually a delusion of being in love. The patient firmly believes that someone is in love with him. Even if he is severely rejected by the other person, he will think that the other person is testing his loyalty to love. It is more common in schizophrenia.