two's company, three's a crowd

two's company(, three's a crowd)

A third person would make a group of people awkward or uncomfortable, especially when the other two are lovers or close friends. I was worried when the new boy moved into the neighborhood and started hanging out with John and his best friend—two's company, but three's a crowd.

three's a crowd

Also, two's company, three's a crowd. A third person spoils the ideal combination of a couple, as in No, I won't join you-three's a crowd. This expression, alluding to a third person spoiling the privacy of a pair of lovers, was already a proverb in 1546. For a synonym, see fifth wheel.
See also: crowd

two's company, three's a crowd

A couple is an ideal combination, which is spoiled by the addition of a third person. This celebration of duality, much used by lovers, found its way into practically all the early proverb collections, from 1546 on. One later version stated, “Two is company, three is trumpery, as the proverb says” (Edna Lyall, Wayfaring Men, 1897); trumpery means excessive frippery.
See also: crowd