S4·E12 Doc's Dismissal/A Frugal Pair/The Girl Next Door

A couple takes a cruise to celebrate its 40th anniversary, but considers breaking up after the husband learns that his wife secretly invested money in the stock market for years. They are now wealthy, but he is furious because he could have retired much sooner. A woman tries to get her husband's attention by claiming that Doc made a pass at her during an examination. A man sneaks on the cruise because he doesn't believe the man travelling with his girlfriend is her brother. He convinces the passenger in the cabin next to theirs to let him stay by claiming to be with the CIA.