Is the marriage of a deceased husband's friend to his widow considered a betrayal of the deceased husband's friendship?

It is permissible for the husband's friend to marry his friend's widow after her iddah (waiting period) ends. This is not considered betrayal, especially if his intention is to care for the children and protect the woman. Marriage is a legitimate act, and if the intention is to honor the deceased friend and care for his family, he will be rewarded for it. What is forbidden is establishing an illicit relationship. If the suitor is pleasing in his religion and character, he should propose to the woman's guardian. She should seek Allah's guidance through istikharah and cut off her relationship with him until the marriage is concluded.