The wedding was a “destination” wedding (I think in the Dominican Republic). Mollie & her boyfriend were supposed to go with the brother/girlfriend. They canceled it because...obviously.
I know, Mollie was supposed to be the maid of honor, the wedding was to be in Dominican, yes. Where is the brother who was also living at the house? He may have been gone since Mollie was dog sitting, but was he?
One scenario could be someone didn’t want the wedding to happen.