live as husband and wifev exprverbal expression: Phrase with special meaning functioning as verb--for example, "put their heads together," "come to an end."
(cohabit as a couple)
同居 tóng jū
夫妻共同生活 fū qī gòng tóng shēng huó
They might as well be married; they've been living for years as husband and wife.