R’ Breuer zt”l was in favor of mixed seating for people who were looking for shidduchim. I’ve been told this before, and a quick search just now found this:
Rabbi Aaron Rakefet of Jerusalem has similarly been quoted as saying that those who eat Sabbath meals in mixed company should celebrate their weddings the same way. He cites the “revered Rabbi Yosef Breuer” as saying that “young people should sit together at weddings [because] mitzvah goreret mitzvah [the fulfillment of one commandment leads to the fulfillment of another]. We want people to make shiduchim [matches]. We want boys and girls to meet. We want dates to come out of this [wedding].”