What is the ruling on a husband lying to his wife for the benefit of the family, in matters other than love, such as saying, "I was with so-and-so," or "I don't have money"? And does the same ruling apply to a wife lying to her husband?

There is no harm for spouses in concealing some matters or in comforting each other with words, as long as it does not lead to the loss of a right. This is based on the Prophet's (peace be upon him) saying: "I do not consider him a liar: a man who reconciles between people and says something intending nothing but reconciliation, a man who speaks during war, and a man who speaks to his wife and a woman who speaks to her husband."

As for lying that leads to the loss of rights, it is forbidden by the consensus of Muslims. One must be cautious not to expand this concession beyond necessity.