Okay, Rita doesn't approve of Brian cheating on her, but adultry with Brian is okay?
Sounds like a plot hole to me.
(Incidentally, Brian's comment about Rita going to Washington, D.C. --- "There are some stars missing on that flag" --- might not be a mistake. Sure, the last state to join was Hawaii, in 1959, but Rita could have been lying about her age when she said she was 50.)
--- C H