in love

A way you feel about someone, more than a silly crush, or just "liking" someone. It's a feeling that you don't necessarily understand. When you are with the person that you're in love with, nothing could make you happier, and when you are away from them, you would give anything to see them.

Person 1: "How did you know you were in love with him?"
Person 2: "I don't know, I guess I just, did."