"It shouldn't happen to me because I go through all of the precautions to make sure I don't end up in this position." What was implied was his belief that Marietta had to be up to something if she actually was pregnant with his child. Zacharias just couldn't see what her angle was just yet, what did she hope to gain from him? Surely, she couldn't be that desperate to find a way into the Smith family - not when it could also go very wrong for her.
"And I don't want to be having this conversation at all." Those words carried his most vulnerable moment thus far. Zacharias didn't like showing any sort of weakness, least it give someone a way to get control over him. However, it would seem that to some extent that he didn't have much say over that at all. "Honestly, I fail to see how this little situation fits into your new outlook on life."