Not to defend Rachel, but it's actually a lot more accepted for women to follow men, be it for work or just cause they are from somewhere else. So if the roles were reversed, I'd be willing to bet people would be like "oh such a good wife, supporting her husband."
And I think it's exaggerating to say they're not isolated in the middle of the woods like it's a horror movie. It's woodsy, yes, but doesn't her brother live super close by? And they see people all the time, based on her stories. Dennis doesn't have friends in Sweden but that's more to do with the fact that he doesn't have a job and he has been traveling to the Netherlands and Aruba very often, so he doesn't seem to have a routine conducive to friends in Sweden. But he goes to his Iron Man thingies whenever he wants. She hardly has him chained to the house.
None of us can know anything for sure, of course, but it doesn't seem to me like he's a victim. He has decision power, or as much as a partner who doesn't bring anything economically can have when they don't want to get an actual job and ergo financial independence and more power.