I agree with most of what pinkhippo said in regards to the nature of the ring, and also somewhat towards the next changes.
I interpreted the ring as being slightly more sinister, however. In addition to changing the MC's body to fit into his environment and to become what people around him want him to be, I think that it also influences the people around him in subtle ways. When he is not wearing it, it makes everything in his life go poorly, thereby forcing him to wear the ring just simply to avoid getting fired or being expelled from school. I think at this point, if he were to go a day without wearing it, it would be something like, "The worst day ever." Which makes me wonder if that might make a good chapter, at some point.
In regards to the changes and the current story, I would prefer seeing the ring take the changes in a new direction, rather than continue down the old Torrid path towards short and fat. I think something like a waifish goth with dark makeup and black hair, lots of piercings, perhaps even a tattoo.
From that perspective, my opinion is that this new job location is a new story or at least "book 2". The first story is imo finished at this point, and you should put those characters and changes to rest rather than going back to them. There are things I would have liked to have seen differently or just more of with the Torrid arc, but I think it's better to just move on and tell a new arc.
In regards to the girl friend, Emily, I feel she doesn't really fit the narrative. I spoke with Oldar in PMs several months ago and he said basically she was an idea for a separate story that he never got to write. He just jammed her into this one in order to play around with her. Personally I think her changes clash with the direction of the MC, and there's not really room in the story to do her properly...
However, I do think the MC needs a consistent friend, confidant, or perhaps even love interest. I actually feel this was a weakness in the original story. Some scenes were needed outside the context of the workplace. College (ie not flunking out) was one subplot that should continue, but we needed one more subplot with a love interest I think, in order to have some variety. The work environment and thus the main changes could change from book to book, but the other aspects of his life should continue to remain as subplots going forward.
As for a "proper ending" or the character getting stuck in a certain body, I don't think that matters, and I wouldn't go in that direction. The simple fact that his life would basically go to hell in a hand basket if he threw the ring away is already a form of stuckage. And that form of psychological prison is imo more interesting and effective than a physical prison.
Plus, I really like the idea of there being a book 3, 4, etc where the character moves to a new job each time, and undergoes a new set of changes each time. I suppose I would angle more for a story that could go on indefinitely, getting a relatively clean slate with each shift in location.