It was
my fault.
You came home late. The wheel stopped and two black eyes followed you across the room. Some apologies need a chorus.

Nugget, a one-year-old hamster who sits in his wheel staring until the sunflower seeds arrive, stuffs a whole cheek with cardboard, and freezes when the cat's shadow crosses the wall. His person was late with the seeds.
Is this a joke product?
It's a real song about a real animal. Whether it's funny depends on what you tell us and the genre you pick — people order these for a laugh and end up keeping them.
Can the apology be to a person, about the pet?
The song is sung by you to the pet. If the apology is really for the person who loves the pet, they'll get the joke — send them the page.
How specific should I be?
Very. 'Forgot the seeds and moved the lamp' makes a better verse than 'was a bad owner'. Two of your details go into the lyrics as you wrote them.
What comes with it?
Two versions of the song, a cover with their photo, a lyric sheet with a QR code, and a page you can send. Thirty seconds free before you pay.