Sweeping statement police alert:
Work songs, travel songs, songs of yearning, nostalgia, regret, despair. Murder ballads, revenge songs. Political songs, social comment, historical songs, fantasy, religious songs.
I am not a list person, but could give you examples for all the above.
Anything can be a subject for a song (thankfully), the fact that a great majority of popular songs are about love doesn't mean that is all they are or can be restricted to.
Bah humbug.