If he loves you.

(most of the things combine)
He won't leave you alone, he'll pretend it was an accident when he sat next to you at the concert or in class, he wont stop stareing and smiling, he blushes when you touch him, he looks down at the floor when you catch him, he stops you in the hall just to say hello, he buys you things, waits all night for you to log into aim, Calls you for no reason at all, and when you play hard to get....he gets sad. And doesn't stare at all anymore.

Froma true experiance I know.