长时间的孤独导致了他内心的不快乐。

Long periods of loneliness caused deep ___unhappiness in his heart.

她长期的不快乐让她难以享受生活中的简单乐趣。

Her constant ___unhappiness makes it hard for her to enjoy life's simple pleasures.

长期加班是导致她不快乐的主要原因。

Working long hours is the main cause of her ___unhappiness.