When an owner suddenly starts to abuse their pet yukkuri, but not for discipline or punishment.
In "pet betrayal", the pet generally didn't do anything wrong. Rather, in this case the owner never actually loved their pet in the first place. These abusers intentionally make their pets happy so that their subsequent abuse will be much more psychologically painful.
Alternatively it could be because the owner suddenly turned from a yu-lover into an abyuser for various reasons.