Very close runner up for me is
Many love songs are about the early stages of love. The stages where your breath is taken away. Or about love lost and regret. This song is about an established, mature and ongoing love. It is the place where we live the bulk of our lives, if we're lucky.
"I feel wonderful because I see the love light in your eyes, and the wonder of it all is that you just don't realize how much I love you"