The young couple is used to mixed dancing and it seems normal to them. They may agree to a separate dancing at their wedding to accommodate the guests who have a sensibility to this, although their inclination is otherwise. Still, in the social world of the couple mixed dancing is the norm.
Just to clarify, I am in no way condoning the outlook that I described, and which belongs to many who call themselves MO, and I think it is sad that these young adults feel they have to resort to lounges and mixed dancing for entertainment.