爱你成痴念你成魔
[ài nĭ chéng chī niàn nĭ chéng mó]
'Obsessed with You: Missing You Turned Me into an Obsessive Soul'. This implies someone is so desperately in love with a person that their longing for the beloved turns extreme. The user's mental state is completely dominated by emotions toward the other party, almost to the point of obsession. It's often used when people feel they've gone beyond healthy levels of love into unhealthy ones.