In the past I have asked my partner a quick question in front of his mum. Say I'm buying something for the house and want his opinion on price. So I'll ask "is this alright?" And show him my phone. He says yes or no and that's that. His mum will ask what we were talking about and then wants to discuss it. How do I tell her I don't want to discuss something with her? Or that it's just between me and my partner without sounding rude?