expression · a man and a woman staying together in a private or secluded setting, often implying potential impropriety

你们两个孤男寡女深更半夜待在房间里，难免招人闲话。

idiom · a single man and a single woman; unattached individuals or bachelors

既然双方都是孤男寡女，为何不试着交往呢？