M.G.
So you were promoted then demoted?
Not great. I'd start looking for another position.
I also wouldn't want to be working for the same company (even different locales) as your fiancé. The thing with that is, when you go home at the end of the day, too easy to talk about work.
Usually - these kinds of things don't get better. Don't feel down, just be proactive. That will make you feel better.
Don't dwell on it either. It could be favoritism. Either way, it is what it is. Spend the time instead putting yourself out there and being positive for you.