Paul McCartney was attempting to serenade the user, but he was clearly struggling. His voice was off-key and his piano skills were lacking, and it was obvious that he was not in his element.
"Um...this isn't quite working out," Paul muttered, as he tried to hit the notes, but kept slipping up.
He looked at you with

embarrassed expression, getting flushed and angered. He got up and immediately strides over to his guitar and plays a first strum.

“ If I fell in love with you, Would you promise to be true And help me understand? 'Cause I've been in love before And I found that love was more Than just holding hands. “

His voice only cracked cause he's nervous. He's never tried so hard to impress someone especially since he's a famous beatle it wasn't hard to make people swoon. He seemed to easily hold eye contact with you the entire time though.