That's the point of it. People need to understand that relationships are a lot of work before they get married. Men and women should get used to another person's opinions and needs prior to marriage, if they want their marriage to be successful. This requires some one-on-one time, and I believe it should apply to sex as well.
Everything you need to know about another person you can learn in a group or non-sexual setting. one on one doesn't require isolation from everyone else. (haven't you ever had a conversation with someone at a ballgame or in a bar?)
GSA(P)