Spoiler alert he's not a dog again lol
He was literally told he could never go back to bein' a dog and that the decision could not be taken back. I'm pretty sure he just pulled a switcharoonie on them and dipped. That and even if he was a dog again I don't think he'd ever let redhead touch him-- memories or not he'd still get a bad feelin' from him 'cause of his severe loathing for him.
Yee it's why the dog god wanted the choices to be made for themselves and not someone else's sake when a dog got the chance to become human. It's not somethin' that can be undone. He even drives this point home when he tells Jonggu that a good percentage of the time the dogs choose to go back to bein' dogs for good.
At this point, I kinda don't want Jeonggu to be with this fucking uke! I think I'll give this webtoon a rest for now because this uke is really getting on my fucking nerves!