Why do nobles not marry even after a banquet?

Nobles do not use ordinary residents' monthly automatic pairing. Choose a noble banquet with a marriage chance and have eligible unmarried adult men and women attend. Race, kinship and other pairing conditions still apply; success is not guaranteed at every banquet. Ordinary automatic pairing requires happiness strictly above 50, or strictly above 60 after Free Love is unlocked. Cat people do not use this ordinary pairing process.