It's wrong to keep secrets from your future spouse.
Mindy has a daughter from her prior marriage and has agreed to marry Sam soon.
Mindy wants to decide where to accommodate her daughter.
Mindy tells Sam that she has a daughter when Sam proposes to her, and that her daughter will live them after marriage.
Mindy asks her parents to take care of her daughter and doesn't tell Sam the she has a daughter.
Sam thanks Mindy for her honesty and happily accepts her daughter as his stepdaughter.
Sam feels betrayed and offended after knowing Mindy has a daughter, and decides to break up with her.