"...he had purchased independence by uniting himself to a rich woman of inferior birth."

In the end, I cannot say I approve of him "purchasing" his independence. I am particularly on the lookout to see if this means something or is just a clever turn of phrase...

It seems to me, he was on the hunt for money. I don't blame him for not wanting Sir Walter's company or daughter. A purely mercenary marriage is something to make me question him.