IMO - these feelings are more about you and your past than they are about the relationship your bf has with his family... please try to look deeper within your self and find the source of this painful discomfort and put a stop to it - it being the unhealed wound(s) that are and will forever stand in the way of this relationship and every relationship to come unless faced dealt with and healed.

BTW - I speak from experience... ((( hugs )))