Quotation su Isaia 61:3

One needs to place ashes on the head of the bridegroom in the place where the tefillin sit in memory of the mourning of Jerusalem. As it says (Isiah 61:3) "To appoint unto them that mourn in Zion, To give unto them a garland for ashes". Rem"a: There are place where is it customary to break a glass after the sheva brachot [the blessing that make up erusin], and this is the tradition in our lands that the bridegroom breaks the utensil on which the blessings of erusin were said. Every place goes according to its traditions. There is also a tradition to fast. See also (siman 61). For the law of throwing food before the bride and bridegroom, see (Shulchan aruch, Orach Chayyim, 171).