I’m in Oviedo! They have a nice language exchange group here that meets 2-3x per week, which might be a good way to practice Spanish and meet people :)

I think the best bet is to become civil partners, that way his visa won’t be tied to an employer. Once you’ve got the papers sorted and he’s looking for jobs, one thing he could do is get a US-based job and then use a PEO (professional employment organization) or EOR (employer of record) to be able to comply with all the tax rules. I’m currently in this process in Spain. American companies just pay so much more, so I’ll happily pay the EOR fee