This is no different than a preacher spending money from the collection plate on a fancy vacation. People give away money with out the receiver signing a contract. If you want a donation to go to a specific cause, get it in writing.
I don’t know. Even if he had spent the donation differently, his aim is a “fancy vacation.” A life-long one! Why not use some donations to bribe his family and all those who provided for the wedding? Get some practice using other people’s money to entice.