It's pretty much up to the parole officer. It's possible to bring a motion before the court to try to get permission, but the odds of the court overturning the parole officer are slight. Also, it takes coordination between the parole departments of the two different states to effect a transfer.

Parole officers usually want a reasonable track record of compliance with parole before considering a transfer. Being authorized to hop on a bus to another state the moment you get out of prison? That would be extremely unusual.

If your boyfriend wishes, he can hire a criminal defense lawyer to advise and assist him.