Among the characteristics we value in a friend or partner, loyalty is often the first. Most things can be forgiven if they were driven by loyalty, while there are few insults worse than to be accused of disloyalty.
This can be traced back to the teachings in the Bible, and in particular, the interaction between Naomi and her daughter-in-law Ruth. Following the death of two of her sons, Naomi instructed their widows to return to their families and remarry.