Several songs are in the "I'm really sorry we can't be together" genre:
. . . because I'm too poor ("Dawn [Go Away]")
. . . because you're too poor ("Rag Doll")
. . . because you love somebody else more than you love me, so stop staying with me out of pity ("Opus 17 [Don't You Worry 'Bout Me]")
. . . because I'm married ("Bye Bye Baby [Baby Goodbye]")
They visit the always-fruitful song-mine of "My dad told me to stop being such a pansy and letting you treat me like dirt": ("Walk Like a Man")
And, conversely, "I hope you'll take me back after you dumped me for treating you like dirt": ("Working My Way Back to You") and the similar "I hope you'll take me back after you dumped me for cheating on you (but it was meaningless, I swear!): ("C'mon Marianne"), and of course, "I'll generously forgive you for dumping me (after thinking--mistakenly!--that I had cheated on you): ("Ronnie")
There's the extremely popular "It was pretty awesome that one time I had sex with that chick I didn’t know": ("December 1963 [Oh What a Night!]")
Then there's "I dumped you just to prove a point, but then, unfortunately for me, you took it really well": ("Big Girls Don't Cry")
Sure, there are a few songs about being in love and all happy, but on balance, these songs are either very pitiful or very jerkwaddy. It's somewhat mystifying how they can be so catchy!