That said I think within the realms of a story it would be easy to construct the Crusade as a good thing from the perception of the characters.
The danger that I see is that you might be accused of white washing the actual events in the attempt to make things palatable from the female character's POV.
The Crusades are an origin period for some interesting knight orders. I just don't know if the Crusades themselves were essentially much better or different than other sacks, except that the people being sacked weren't even Christians.