Question: how to know that guy is falling for you?
Answer: He's a perfect gentleman. He is working hard to make a lasting impression on you. ... 
He loves how weird you are. ... 
His body language is all off. ... 
He gives you all of his attention. ... 
His smile says it all. ... 
He can't sit still. ... 
Your sex life is off the hook. ... 
He wants to protect you.