Is there any chance that you can keep your current job and work remotely?
If OP wants to live in SK with his fiance and work remotely for somewhere else, they'd probably be better off being a "tourist" and getting married and getting a SK visa that way. Yes, they're engaged because they didn't want to rush into that, but lots of people from different countries end up getting married in a hurry for this reason.
https://www.justlanded.com/english/South-Korea/South-Korea-G...
I’m not saying it’s ideal, but you’re trying to pick the least bad of some dreadful options (for which I’m sorry and wish your fiancée [and you] well as you navigate this). Keeping your current job, working it as a “second shift” job from Korea might give you stability that’s valuable here.