After a wedding, the bride and groom observe a seven-day period of celebration, during which the "Sheva Berachot" (seven special blessings) are recited with Birkat Ha'mazon at the end of every meal.
The question arises as to whether these Berachot should be recited after a meal on the final of the seven days if the meal ended after sundown. Since the eighth day has now begun, is it perhaps too late to recite the Sheva Berachot, which relate specifically to the seven days of celebration. Alternatively, one might contend that since the meal began during the seventh day, it warrants the recitation of Sheva Berachot even though the meal ended after the eighth day had begun.
At first glance, we should perhaps apply to this case the ruling of the Shulchan Aruch regarding a similar situation, of a Se'uda Shelishit meal that extends beyond sundown late Shabbat afternoon. The Shulchan Aruch in siman 188:10 writes explicitly that even though in such a case one recites Birkat Ha'mazon after Shabbat has ended, he nevertheless adds the paragraph of Retzei (the special paragraph added to Birkat Ha'mazon on Shabbat), since we determine the status of Birkat Ha'mazon based on when the meal began. Seemingly, then, in the case of Sheva Berachot, too, the Berachot should be recited even after sundown on the seventh day if the meal began before sundown.
However, Rabbi Moshe Halevi, in his work Birkat Hashem, Helek 4, page 397, draws a distinction between the two cases. When it comes to adding Retzei, what is at stake is merely the addition of an extra paragraph within a Beracha of Birkat Ha'mazon. The Shulchan Aruch likely allowed reciting Retzei in such a case because one does not run the risk of reciting a Beracha unnecessarily. In the case of Sheva Berachot, by contrast, the question involves the recitation of seven Berachot, and we should therefore apply the fundamental rule of Safek Berachot Le'hakel, meaning, that we do not recite a Beracha when its requirement is subject to uncertainty.
Therefore, Rabbi Moshe Halevi rules that the Sheva Berachot are not recited after a meal that began on the seventh day since the wedding and ended after sundown, since it is questionable whether these Berachot are warranted in such a case.
This is the opinion of Rav Hida in Birkei Yosef, siman 188, seif kattan 14.
