It is could to hear that the Clicker Training is working and that your Boyfriend can get him to step up without biting.
It just sounds like the Grey prefers you, but also understands your Boyfriend is his primary care giver, just not the one your Grey wants to "Neck" with. ;-)
So, patience and time will build trust and closeness between your Boyfriend and Grey. But, just do as Beccy suggested and avoid cuddles for now.
Time and Patience are the key with Greys :-)