Exodus 21:8 "If he does not designate her for himself"

The Torah is concerned with the well-being of Jewish daughters who have been sold as maidservants and provides them with an opportunity to be freed from slavery. Her master is urged to marry his maidservant or give her as a wife to his son. In this way, the girl's slavery may prove to be beneficial for her, showing her the guiding hand of HaShem.

Her unfortunate experience of slavery may actually bring about her meeting with her future husband!