Yeah, and if OP had done that then it would be unreasonable too. But that’s not what happened.
OP set a boundary and entered into the relationship on the basis that he said he wanted the same thing as she did. She didn’t say “oh, well, he wants to live in Norway, I want to live in London, he has to put up”.
He’s now changed his mind. Fine. But he has to decide whether it’s more important to him to live in Oslo or to be with OP. It is very unfair to demand she change her preference (which he’s doing), tell her she’s the problem (which he’s doing) and make it her problem to dilemma to deal with.
It’s not that he changed his mind that makes him unreasonable. It’s that he’s changed his mind, issued an ultimatum, unilaterally dictated that they change the status quo and agreed upon plan…
There are a thousand mumsnet threads that say changing the status quo (whether it’s moving house, having another child, opening the relationship up to swinging/polygamy or someone being a SAHP) is a “two yes, one no” situation. If the person wanting to change the situation, away from the previously agreed situation, doesn’t have agreement then they decide whether to leave and get their way or to stay and sacrifice it. You would absolutely never, ever, ever see an OP on here saying she wants another child and DH doesn’t being told it’s reasonable to force him to have one. Never. Nor would you ever have an OP preparing to go back to work after maternity have her DH demand she give up work and be a SAHM and being told she should just do it even though she wants to go back to work.
The only basis people have called OP unreasonable for is that they like Norway. Yet, bizarrely, despite saying how much they’d love to live there - they don’t live there. I wonder why. Maybe it’s because they have lives, family, friends and careers here - just like OP!