Most Helpful Girl
I don't know all of your situation at hand here, dear, however with what you are saying here, dear, it sounds like for 'Four years now' and still counting on, he doesn't want to share some of his life with you, meaning his family, because this would mean he may feel then he would be Committed wholeheartedly, and he isn't ready nor raring to do it at this time.
It could all change of course, however, you may need to to give things a push to test him and your relationship. Tell him you want to meet the parents, it's time they knew you, or you may be testing the waters elsewhere... Life is too short.
Good luck. xx0