Ménage à Trois
Two is company and three is a crowd... Is it a saying used to suggest that it is better to be in a group of only two people than to have a third person with you as well? It is used when two people are relaxed and enjoying each other's company but another person would make them feel less comfortable.
But do not tell Ryan Scoats, who earned undergraduate and masters degrees and is involved in penetrating research at the University of Bath, researching masculinities under Professor Eric Anderson.