One parent
You may have noticed sometimes that when your baby cries, only the mom can sotthe him up. When her dad picks him up, she would burst into more tears. It seems like she’s regarding her dad as a total stranger. Well, it is indeed heart breaking. But, this is a common scenario. Babies show their preference for one parent over the other at around 7 - 8 months. They would want to be with the person with whom they would feel secure, familiar and comforting. Basically, they would tend to be with the mother more since their dad is at work most of the day or vise-versa.
If this happens, the parent who is not so much preferred must understand that this is a normal reaction of a child. All he or she has to do is to make up for the time lost and try being close to the child whenever they have the time.