Is the husband entitled to obligate his wife to a specific diet and require her to seek his permission to eat food outside of it? And is the wife sinful if she disobeys or does not inform him? And is it obligatory for her to seek his forgiveness, or is seeking forgiveness from Allah and repentance sufficient?

A wife must obey her husband in what is right. However, a husband's obedience is not absolute, except for Allah and His Messenger. The wife's obedience to her husband is subject to three conditions: that he does not command her to disobey Allah, that the command is within the wife's ability and does not cause her harm, and that the command pertains to marriage and its related matters. Based on this, a wife is not obligated to obey her husband in following a specific diet unless the matter reaches the point of illness. The relationship between spouses should be built on understanding, affection, and mercy.