A lot of the time I will go to houses that are having difficult relationships with their dogs and mostly this is caused by inconsistency. I am saying that one person is strict and has a dog working for treats, while the other person is basically tossing treats their way just for breathing. Much of the time, this is the same thing that is happening when it comes to rules and safety. The dog has different rules with different people, but in the same house.
Dogs want clear communication with you, this is where you need to start making yourself aware of what you are doing. I always recommend to video a short session with the client working the dog and start to notice what you do.
Some basic things to look for:
How many times are you saying a command? (I have counted someone saying “sit” 9 times for 1 sit)
What does your dog do to get rewards? (I am referring to behaviorally not just being cute)
What does your dog do to get their bowl of food?
Are you having patience with the dog?
How soon do you give a reward/correction/marker after the behavior?
Inconsistent actions create mixed messages, so everyone needs to get on the same page.