Legal Question in Real Estate Law in Oregon

I do not really know for sure, but I see that no one else has answered your question. I would first call the Oregon DMV and ask them what to do. There may be a form for this exact situation.

I do not know what you mean by "primary signer." I assume you mean that only his name is on the title (and not yours). Are you on the title at all. Are you listed as the holder of a security interest?

If not, you could go to the county clerk and say that you want to file a lien on the car to secure repayment (by the owner) of the amounts you have paid for it. Then file to foreclose the lien. The asset (car) would then be auctioned off at the county courthouse, where you will buy it for $1, unless your boyfriend comes forward and pays off the lien in the meantime. The county clerk will then give you a document showing you own the car. Take that document to DMV and get a title for the car in your name.