I think that people living together for some time can communicate non-verbally in other ways than kicking under the table. An intense eye contact, for example, should basically work as well. If not, this can be discussed afterwards to avoid a similar embarassment later.
As an older adult, I don't like the idea that my partner feels the need to control what I say and don't like the idea of having to control what she says. If I don't agree with what she is saying and have the feeling that she is embarassing herself and possibly ourselves, I can still give my own opinion, openly and respectfully, or gently press her arm to attract her attention. She is usually very receptive to the things I do so I don't need to be very demonstrative to have her attention. We also have no problem with disagreeing with each other as long as it is done with all due respect.
And if it so happens that she embarassed us, then "Schwamm drüber", I don't really care because my love for her is so much stronger than any embarassment she could have created. It is just a question of perspective in the end, isn't it?