Noah didn't want to share it with his mother. He had once shared with her something and it had gone to his father, before he was punished. And though Eve was now married, he didn't see a point to tell about this. He said,
"No. I think it is time everyone stopped expecting and telling me what to do. Fortunately or unfortunately, I am the Duke now and I have responsibilities to complete and at the moment, marriage is not on my mind."
He was mentally exhausted after all these years of having to push and meet everyone's expectations, to walk in the lines drawn for him, that he couldn't do it anymore.
Lady Hilda's expression told everything she wanted to tell her son. But she implicitly let Noah know, "I am disappointed by your action, son. It isn't too late yet, and if you think again, Anaya might change her mind and stay."