By when? The agreement should have said that title should be transferred by a date certain. Did it say anything like that?
I'm not sure by when, or if there was a date.
How did her name get "taken off the mortgage" without her name being removed from the title? It would be extremely unusual for a mortgage lender to release a borrower solely because of a divorce and only slightly less unusual for a lender to allow one (ex-)spouse to refinance in his name only without the non-refinancing (ex-)spouse being taken off title.
I have no idea, but that's what happened. I checked the public property records and she was discharged from the mortgage and he was able to refinance by himself. The records also show that the deed is still in both of their names.
The question doesn't make any sense. A statute of limitations is a law that (a) in the context of criminal law, provides how long after a crime is committed the prosecution has to file charges, or (b) in the context of civil law, provides how long after accrual of a cause of action the plaintiff has to file a lawsuit.
Is there a deadline by which your boyfriend's ex should have given him a deed for her interest in the property? You'd have to tell us because we obviously don't know what his settlement agreement says.
Is there a deadline after which the obligation in the settlement agreement might no longer be enforceable? I don't know. Your boyfriend would need to consult with a New Jersey family law attorney about this, but the big question is why he has allowed six years to pass without dealing with this situation. Can you shed some light on that? When was the last time he asked his ex to provide a deed that transfers her interest, and how did she respond to that request?