]She doesn't care what kind of men her daughters marry, she doesn't even care that her favourite daughter is doing wrong! as long as she is married!

I think that mrs Bennet cares a great deal about the men that her daughters marry, only her idea about a good man, might not be the same as most peoples. She's not clever enughf to understand the fact that he probably would have left the girl, she only sees the handsome, young, read coat who she knew before and that man is someone who everyone liked.