In the Book by Hanoch Teller about Rav Shlomo Zalman Auerbach
He talks about some fund raising dinner where there was mixed seating.
One of Rav Shlomo’s talmidim complained to the Rav about the mixed seating and how could this be allowed. Rav Shlomo gave the talmid a sharp lesson in Dereach Eretz, and then sat next to his wife (Rebbetizen Auerbach).