I believe this song is about a relationship either growing old and getting boring for one of the people, or where one person has straight out from the beginning never been that interested in the other. He/she goes through the motions of buying birthday presents and cooking up dinner, but when they see their couple they don't really feel anything for them. The joy comes basically from having someone 'under their thumb' and that person's love is wasted on them because they're so easily replaceable.
I believe this song is about a relationship either growing old and getting boring for one of the people, or where one person has straight out from the beginning never been that interested in the other. He/she goes through the motions of buying birthday presents and cooking up dinner, but when they see their couple they don't really feel anything for them. The joy comes basically from having someone 'under their thumb' and that person's love is wasted on them because they're so easily replaceable.