OP, normally I’m the biggest proponent of moving overseas using grad school as the vehicle, it’s a near perfect way to change careers and see the world. However, there’s lots happening here:
1. Your SO is significantly older to be changing careers. So, say he does this and he finishes and is now around 41-42, hunting for jobs back in the US, starting from the bottom against younger applicants. It will take a bit to get to where he thinks he should be at his age, don’t underestimate that, it weighs on the mind. Also, not sure how well this will be perceived back in the US? Empowers will wonder why Europe, couldn’t you get into an American school? Oh, you wanted to explore Europe, maybe work isn’t your priority? Atypical pathway will invite scrutiny, especially in the US where that’s seen as a negative instead of a positive.
2. Where do you and the relationship fit into this? If he was single, it’s one thing. As the trailing partner, do you join or do you both have a long distanced relationship for a couple years? If he’s single and living out his dream of being in Europe, it can be fun as hell. If you’re with him, it would be great too, but what are you doing? Working? School too? Is this your dream?
3. Is now the best time? This pandemic isn’t going anywhere soon. International travel and relocation will be rather challenging for the next two years. Also, being an expat, even for school, can have its challenges. What country will this be in, what’s the language, how adaptable is your partner, and how much cultural and emotional intelligence does he have?
Without more info, I’d lean towards not conflating the two. If he has a niche of financial analysis in marketing, build on that to create something that would be valuable to any marketing company. See if there’s new opportunities in a new company that has overseas work or will let you work virtually. Explore what types of free or cheap resources are available to grow in a the desired area.
As for the experience of living in Europe, I’d out that off for a couple years, sort out the job thing with the focus on finding a flexible career or pathway. Then, when the dust settles, looking to be a digital nomad and explore working while traveling.
Also, be clear where you fit into this. The greatest reason expat experiences fail is if the partner or children aren’t happy with the arrangement. Lots of time and money Wasted if things end prematurely.