If she is displeasing in the eyes of her master who had designated her for himself, he must allow her to be redeemed. He has no right to sell her to foreigners, since he has broken faith with her.
Jewish Publication Society of America Version (JPS1917) - Exodus 21:8 >If she please not her master, who hath espoused her to himself, then shall he let her be redeemed; to sell her unto a foreign people he shall have no power, seeing he hath dealt deceitfully with her.