Married couples usually share household responsibilities together.

married 是动词 marry 的过去分词形式，表示"结婚的"状态。 couples 是名词 couple 的复数形式，指"夫妻、伴侣"。 married couples 指"已婚夫妇"，强调已经缔结婚姻关系的伴侣。