chiyuv of mezonos

Kesubos 2 explains that if the wedding date arrives and for some reason of ones a postponement is necessary, the ba’al is still obligated to support his wife with mezonos from the original date onward. The Divrei Yezechkel poses the following chakira: is this obligation of mezonos because we create a legal fiction of the marriage having occurred, or is this a separate chiyuv of mezonos above and beyond that which applies in a normal wedding case?