And of what it might be Sir Rowland had grounds upon which to found at least a guess.

Had perhaps Wilding acted upon some similar feelings in avoiding the duel?
He wondered; and when Richard dismissed Diana's challenge with a fatuous laugh, it was Blake who took it up.
"You speak, ma'am," said he, "as if you knew that there were reasons, and knew, too, what those reasons might be." Diana looked at Ruth, as if for guidance before replying.

But Ruth sat calm and seemingly impassive, looking straight before her.

She was, indeed, indifferent how much Diana said, for in any case the matter could not remain a secret long.

Lady Horton, silent too and listening, looked a question at her daughter.
And so, after a pause: "I know both," said Diana, her eyes straying again to Ruth; and a subtler man than Blake would have read that glance and understood that this same reason which he sought so diligently sat there before him.
Richard, indeed, catching that sly look of his cousin's, checked his assurance, and stood frowning, cogitating.