They're now saying that the 21st century is going to be the century of what they call the "symmetrical marriage," or the "pure marriage," or the "companionate marriage."
有个说法就是，21世纪 的婚姻可以被称为“对等婚姻” “纯洁的婚姻”也可以称为“彼此不承担法律义务的婚姻”