] it does seem an unwise for Mrs. Dashwood to ignore the financial differences, but her own experience supports her sensibility and views. She married Henry Dashwood and as per the second paragraph of Chapter 1, she brought nothing into the match. It makes sense that Mrs. Dashwood would think that if she could marry well with nothing, why couldn't her daughters.

It's also one of her cherished beliefs about sensibility. For Mrs. Dashwood it was "contrary to every doctrine of hers that difference of fortune should keep any couple asunder". It's as though there is something more romantic in the idea of a wealthy man being willing to marry a girl just because he loves her and not for any potential material advantage she might be to him.