It's discouraged from asking pointed questions about other people's relationships.
Sam is talking to a couple he just met in a cafe.
Sam wants to ask the couple about their relationship.
Sam asks the couple where they met and other normal questions people tend to ask couples.
Sam asks some probing questions about the couple's sex life.
The couple feel comfortable with Sam's questions and tell him a bit about their relationship.
The couple thinks Sam is creepy for asking such personal questions when they hardly know him.