Love and sex and relationships are fine, fine subjects for a song. But we're not hurting for songs about heartbreak and longing and desire. There are plenty. Seriously.
What we don't have enough of are songs for people who are happily married to sing along to when crunching on a deadline, staying late to finish a project, or pondering an impending reorg.
The only one that springs to mind is Nothin', by Reel Big Fish, which has the chorus that goes: "And I don't f*ckin' care, and I don't f*ckin' care, and I don't f*ckin' care anymore." Cathartic, but not really an all-occasion kind of song...
(I played it a lot when I was in the final stages of thesis-writing.)