Lotta people in this thread that I’m surprised are in successful relationships.
This isn’t a girlfriend, this is his fiancé. Partners should support each others dreams and aspirations. And yes, those going after their dreams should also understand when they need to compromise.
The key factors include how much this Rochester training is actually on her aspirational path, or is it just “yeah, that’d be cool.”
If it truly is an amazing opportunity that she feels like she’ll be letting herself down if she passes up, then some compromise on OP’s part is reasonable under the idea of supporting your partner/spouse.
If it were me though, I’d look at other options. Maybe one would be an acceptable alternative for a compromise. As Broc said, I’d be very surprised if Rochester really is the most prestigious or best opportunity for this type of training.
Then, if it really is part of her dreams, and is the only reasonable option, then OP has a compromise to consider… but establish bounds to the compromise. He needs to make it clear that it would be temporary. Do not buy property, just rent. Be very firm that even if the training turns into a job opportunity, you move after the training.
But, that’s just me. I can stick it out in the suck for a little while to support my wife. I expect the same from her.