I struggle with this too. I think Gr3tta's advice is good, to have your partner treat the child part as a child, with appropriate body language and such. Does your partner know about the child parts, or when they are out? They may need help recognizing when the little ones are out and when it would be good to change their approach -- my hubby and I are working on this, too. Partners may only see it as a mood change or similar and not realize how to approach the child part.