He's so madly in love that he is blinded ( by the color yellow), his love is like a color that takes over everything, and leads to him not be able to control himself, and have to confess his love in so many ways. It shows his loss of control, vulnerability and need for this other person. It has a hint of pain and hope within. In short,
I see this song as his need to confess his love, a love that has completely taken hold of him.