He has a crush on her. Picture the scene.
Oh, I just want you for my own
More than you could ever know
Make my wish come true
Baby all I want
At the climax of the song, she turns to him, points and sings
is You, You baby!
His little heart is complete. She wants him too! Then, sadly, she turns and points at everybody and sings about how she wants them all too ("and you", "and you", "and you"). The little soul is both devastated and frustrated. "Women" he's thinking. Poor soul. You can watch his devastation again and again if you wish:
He only learned how to play the drums to impress her and is left unhappy at this apparent rejection. Of course, he later gets a kiss on the cheek so all is well (although he could have tried to smile at least):