A well-known Halacha establishes that the mourning period after the death of a parent, Heaven forbid, extends for twelve months, whereas for other immediate relatives one observes mourning for only thirty days. There are two possible reasons for why Halacha requires a longer mourning period for a parent. One possibility is that this requirement stems from the Torah command of "Kabed Et Abicha Ve’et Imecha" – honoring parents. As part of the general obligation to show respect to parents, one is required to observe a special period of mourning for a deceased parent, which is longer than the period of Abelut (mourning) for other family members.
Alternatively, however, one could suggest that the extended period of Abelut has nothing at all to do with the Misva of honoring parents. Rather, mourning is a function of closeness, and thus the extended period of mourning for a parent is a natural result of the special closeness that a child feels for his or her parent.
Rabbi Moshe Feinstein (Russia-New York, 1895-1986), in his Iggerot Moshe (Yoreh De’a 255), notes the practical difference between these two perspectives on the extended period of mourning. Generally, once a woman gets married, her responsibility to her husband takes precedence over her obligation to honor her parents. If a husband makes a request of his wife that is in opposition to the wishes of her parents, she should obey his request despite her parents’ objection. Therefore, if we view the twelve-month mourning period as an application of "Kabed Et Abicha Ve’et Imecha," then it would not take precedence over a wife’s obligations to her husband. For example, if a husband is attending a function such as a dinner or a wedding, and he wants his wife – who is within the twelve-month mourning period – to join him, she should attend the function, according to this approach. Even though the restrictions of Abelut generally forbid her attendance at such a function, her responsibility to her husband supersedes her requirement to honor her parents by observing this period of mourning.
If, however, we view the twelve-month period of mourning as simply a function of the closeness of the parent-child relationship, which affects the obligation of Abelut irrespective of the Misva of honoring parents, then the husband’s wishes have no effect upon a wife’s observance of Abelut. The husband has no right to force his wife to violate the requirements of Abelut, and she would thus be forbidden to attend the affair, despite his insistence.
Rabbi Feinstein writes that since he has not seen this Halacha discussed explicitly in any Halachic source, he cannot definitively rule on the issue. He thus concludes that a husband should not insist that his wife join him at a function during her period of Abelut, but if their Shalom Bayit (marital harmony) will be adversely affected by her not attending, then she may. Since this issue cannot be definitively determined one way or the other, the wife should not attend, but there is room to be lenient in the interest of avoiding marital strife. This is also the ruling of Hacham Ovadia Yosef, in Yalkut Yosef (listen to audio recording for precise citation).
Summary: During the twelve months after a parent’s death, Heaven forbid, it is forbidden to attend a festive event, even if one’s spouse wishes that he or she attend. If, however, this might affect the couple’s Shalom Bayit, the mourner may attend the affair.
