The other cat went merrrrrrrwwwowwww at him, forcing him to walk away slowly over the course of 10 minutes.

Most catfights involve a lot of hissing and spitting and no actual contact.

Not a vet, but I imagine it looks like a perfectly healthy cat moping around like it’s about to die. I had a cat years ago that would get depressed anytime he would snap at my dog and then subsequently get snapped back at.

Maybe it was a online fight