I need your insights...what do you think I should do?

Take her out to lunch in the middle of it, it will be a nice break and it will show her how much you appreciate her, It's funny because i go through the same thing with my mom whenever we have company, i can't stand it and everyone is on thin ice with each other, because i have two sisters, too. But when we take her out to lunch, we step away from the house and kind of forget about it for an hour, its relaxing and lets us talk and joke around.