I really hope that do!
Spoilers...
Yep, Renald and the Duke did regret the way they treated Penelope, especially Renald. He is the second one to apologize to her after the Crown Prince for all the pain and suffering she had to endure because of him and supports her during the final battle with the main villain by fighting alongside the CP. However, Derrick remains a total dick almost throughout the entire novel, calling Penelope an attention whore and supporting Yvonne until he was back stabbed by her. Only then did he finally 'realize' that Penelope was the one he should've trusted. It is during the side stories when he finally apologizes to her but Penelope, like the queen she is, does not accept his apology even going as far as saying that she will never forgive him.
Damnnnn I can wait to see the look on his face(๑•ㅂ•)و✧
So now that we know who the ML is I wanna know what happens to the brothers and father did they get what they deserve?