Why does Mrs. Harling fight with Antonia in chapter 10?

Ántonia starts going to the dances all the time, and people begin to talk about her. Boys start hanging around the house at all times, and one night Mr. Harling happens to see a boy jumping over his fence. Ántonia explains that an engaged man had tried to kiss her after walking her home and she had slapped him. Mr. Harling tells her that she is hanging out with loose women and that she is getting the same reputation. He forbids her from going to the dances, and the next day Mrs. Harling backs him up. Ántonia decides to leave to go work for Wick Cutter instead. Mrs. Harling warns her that Wick Cutter will likely get her pregnant, but she is unable to change her mind. Mrs. Harling is bitter that she let herself grow attached to Ántonia.