for the sister: she's the daughter of their mother and his step father. the step father passed away in a car accident when the sister was rather young (i didn't say an age) and the mom became a drunk so he raised her. that's the only facts i have.
for the ex fiance: she was a woman who he had met in a bar and they became close. they were friends at first then it developed. he was in love with her and right before the wedding day she kind of just ghosted him for an unknown reason.