I know you. - You're in love, but they don’t know you like you know them.

You're in love, but they don’t know you like you know them. They’re just kind of there, and you're stuck in the 'I know you' phase.

I know you. You like me, but you don’t know how much I like you.

I know you. You’re the one who smiled at me but never said hi.

I know you. You’re the one who saw me at lunch but never came over.