an unhealthy father/mother and son bond

I married my husband 2 and a half years ago. he is an only child and I have gone through hell with his parents bc they seriously could not let go of their son. they could not grasp that when he got married he needs to be with his wife. till this day the issue is still there. but it's not normal the connection the parents need to their 30 year old son. I was wondering if there happens to be a medical term for this kind of attachment/bond? thank g-d my husband has learned to create a distance but how his parents r and act we can't change that.