Back then, if the family was in dire financial strains, she could be sold, but was protected (could not go to foreigners, and was required to be treated as a daughter) and of given in marriage to the son, he must treat her as a wife of let her go for free.
So while I get your point, do yourself a favor and keep reading.
On the surface, I did think it was wrong, but this was a social construct already well into place -- God allowed it but made laws, even instituting the death penalty, to regulate it.
The reason why this was allowed is because God promises to abolish all these things permanently (Rev 21:3-4).
In the meantime, he simply put rules into place.