Sidney arrived at Ash and Abigail's wedding with the simple expectation that she'd see her friends get married and wish them all the best. Getting caught serenading the fish in the aquarium was one thing she did not expect to happen. She certainly didn't expect the person who caught her to be a handsome businessman who instantly wanted to hire her for her vocal talent. Truth be told, she didn't even think she had any vocal talent. Most of all, she by no means expected to fall in love with the aforementioned businessman.
But sometimes, the unexpected happens. Sometimes, a lot of unexpected things happen. Sometimes, you show up to your friend's wedding and your life changes forever.