Hmm... I wonder if it's any good the engagement with Nell is maintained. Maybe it would be better for both of them not to. There could be too much baggage. Herbert could feel forever apologetic toward her, which isn't good for a healthy relationship. Nell might fear a relapse for the rest of her life. Like if she said one wrong word, it could be the trigger to push Herbert back toward a collapse. Not to mention she simply might not be able to forget all of his scumbaggery, so even if he did a little innocent mistake, she might throw a nasty line at him, asking him if he really did change, after all. That's no good for a marriage. Who knows how such a marriage would affect their children. We already have a bad example of poor parenting in Herbert himself. She certainly did blush due to the princess's teasing, but it could as well be youthful embarrassment and shame, not necessarily tsundere vibes.
Naturally it makes sense Nell's old man would want to stick to the deal. His daughter would marry into the ducal family. Furthermore, Herbert is the talk of the town with the sage's magic. The marquis would be insane to drop such a political marriage.
It's pretty much the same with the poor maid. It could be better if they paid her a good sum of gold and wrote a letter of recommendation full of praise, so she would have no troubles finding a new employer. Now she gets weird treatment at Herbert's mansion. Is that fair in the other servants's eyes? She could get shunned by them. But maybe it all will eventually return to normal. And maybe there even aren't more maids around.