From: Rabbi Moshe Sofer
To: Rabbi Meir
The Chasam Sofer permits a widower to remarry after only two festivals rather than three, employing a mimah nafshach argument: if the waiting period is rooted in aveilus, the great mitzvah of relieving a widow's suffering overrides it and the principle of leniency in mourning supports R. Yehuda's two-festival position; if it is rooted in de'os bamitah, the disruption of the rabbi's household qualifies as 'no one to serve him,' permitting early remarriage. He further demonstrates that the Bavli and Yerushalmi disagree on the underlying rationale, and that the Rif and Rambam's adherence to the Bavli paradoxically supports the lenient ruling.
Source: Shu"t Chasam Sofer YD §349