Visa marriages! I think here in Sweden at least it's not super difficult to get permanent residency via cohabitation, and cohabitation doesn't even require any particular paperwork. Granted, it's been a while since I looked into it, and with a government that's all chummy with the alt-right our immigration rules have gotten tighter, so things might've changed.

I'm hoping with the massive anti-US sentiment going right now, that the next government won't be right wing.