"Lizzy," said her father, "I have given him my consent. He is the kind of man, indeed, to whom I should never dare refuse anything which he condescended to ask. I now give it to you, if you are resolved on having him. But let me advise you to think better of it. I know your disposition, Lizzy. I know that you could be neither happy nor respectable unless you truly esteemed your husband -- unless you looked up to him as a superior. Your lively talents would place you in the greatest danger in an unequal marriage. You could scarcely escape discredit and misery. My child, let me not have the grief of seeing you unable to respect your partner in life. You know not what you are about."

Mr. Bennet is worried about Elizabeth, not only because she is his favorite, but is also the most like him. Respect is very to Mr. B because he cannot feel it towards his own wife.

Jane and Bingley are equally matched in temperment. They will respect and love each other.

Lydia probably won't respect Wickham, any more than he will her. They are both too self-orientated to think of other people.

Elizabeth has not really shown her father that she respects Darcy. She has hidden her changing feelings from her entire family. That is why she needs to persuade her father to her true feelings.