When you are playing doubles, you and your partner need to move in unison to cover the court properly.
To accomplish this, pretend you are “joined at the hip” by a rope eight to ten feet long. If you move to one side of the court, obviously, your partner has to move that way too, or risk “breaking” the rope. Breaking the rope creates an opening between you. This is especially important when you are both at the net. Good spacing will make your opponents try risky down the line shots or lobs and that can create opportunities for you.
So get attached to your partner and cover the court!