What do the reactions of Victor and Sibyl to the spectacle of Amanda and Elyot fighting suggest about their personalities?

The fact that both Victor and Sibyl only watched as their new spouses screamed and struck each other suggests that they are very passive people who are not given to action. From how Victor reacted to the news that Elyot had slapped Amanda when they were married, it seems strange that he watches their violent fight unfold without any interference. Sibyl, too, is not inclined to defend Elyot and can only watch the pair silently.