Next time you play a doubles match and you are playing with a partner who takes the same lessons that you do, do not try to coach them. Assume they know what you know, but they might not be playing well or they might be having a bad day. In that case, too much talking or coaching might be detrimental. In general, if you do not have something positive to say, then do not say anything.
At this point, you would be better off adjusting your game to your partner's instead of trying to fix their game. Trying to fix your partner's game is a good way to lose a good friend.
For example, if you normally like to come into the net, stay back until you are invited. Or, both stay back until you have an opportunity to attack. Too much talking or coaching is not what your partner needs.
Remember this "next time."
Good luck on the courts!