Wedding Money
Strictly speaking, all the various rituals and ceremonies that had been performed were not necessary for the marriage to be valid.
Strictly speaking, to make any marriage valid in the eyes of Adhanian law, the only thing that was needed was a public statement from the boy and girl's guardian, letting the people in the vicinity know that this boy and girl was now man and woman.
But the reasons why the many rituals and ceremonies existed were both cultural, designed to make the day more merry and memorable, and religious, as it was believed that performing such acts would draw the favor of the gods and bestow thier blesings on the newlyweds, resulting in peace and harmony in the house.
And the reason behind Alexander's lavish and extravagant wedding was purposed to awe and impress his guests and retailers.