Q: The Gemara answered that the reason that justified rebbe eliezer's releasing his slave was even though he was violating an aseh, "mitzvah derabim shaani".
Tosafos asks on the behag who says that avilus pushes off second day of yom tov since aveilus is deoraisa and the yom tov is only mederabanan. And he brings a proof from our gemara. But how? By our gemara the deoraisa does not push off derabanan of teffilah is becasue of tzibur. The behag is talking about avelus which is only in concern in regards to the yachid.
And about this i am not sure,Tosafos second answer. But maybe the the reason e chasans mishteh pushes aveilus is because there is also a tzibur aspect.Which would bring back to the question mentioned above.
Shahar, United States
1) The Rosh in Berachos 7:20, on this Tosfos, adds something important. He writes that according to the Behag, the Aveilus pushes off "Aseh d'Rabim Simchas ha'Regel". We learn from this that the Mitzvah of being happy on Yom Tov is called an "Aseh d'Rabim." Simchas Yom Tov is a Mitzvah on the Tzibur, not only on the individual. So according to Tosfos and the Rosh, who disagree with the Behag, the public Mitzvah of Simchah on the second day of Yom Tov pushes off the private Mitzvah of Aveilus.
2) I want to bring a source that Simchah on Yom Tov is a public Mitzvah. The Ramban in Parshas Emor (Vayikra 23:2) expalins the verse, "Mikra'ei Kodesh," "Holy callings." The Ramban explains that the entire Jewish people are called to Shul on Yom Tov to praise Hash-m and feast. This is not merely a personal Mitzvah, it is a communal one.
3) In contrast, it seems that the Mitzvah of the Chasan is a family one, not on the whole Tzibur.
Shahar, wishing you and your family a Healthy Summer and a very good month of Iyar,
Dovid Bloom