Actually, she didn't need to drug him to dull his senses as he was sexually attracted to her back then and was willing to have sex with her. But she wasn't going to take any chances.
She wanted what she wanted at all costs and wasn't willing to allow for failure. So she had drugged him and stole his seed from him.
He didn't say all of that. Instead, he said stoically, "The past is in the past. Like you said, I have changed. I have become a better man. I have you and many other things to thank for that change."
Lady Vena scoffed and gave up.
The sight of the harlot being rebuffed pleased Delia greatly. She wanted to hide it, but her lips couldn't be forced to remain calm. They curved to form a smile. So she had to hide her smiling face with a cup.
She said, "What a shame. It seems you're not as pretty as you think you are. Don't be sad, though. It is a normal thing that happens when you get older. You'll get over it soon."