I get what you mean but it's not true. I am reading the novel so I can tell you somethings are different in the manga. But Dean/Alfred is always helping Iris from the shadows and sometimes outright.
Queen Dowager wanted Mellice as her daughter in law but respected Mellice's wishes that she loved Duke Armelia. When Iris was born Queen Dowager decided to have Iris as Grand-daughter in law. Her intentions towards Iris are positive. Personally I think the Church arc is okay bthe story afterwards gets interesting.
https://www.novelupdates.com/series/common-sense-of-a-dukes-daughter/
There is a prequel as well. Common Sense of a warrior. It's Mellice's story. I haven't read it yet but it seems interesting so I have bookmarked it since it doesn't have many translated chapters.
It was literally good but everything was starting to go like nahhh..I'm literally doubting the first prince because I only see him as someone using Iris as a chess piece to become king and for the revenge( ̄へ ̄)and as for the Queen Dowager all I got to say is she's also strange very very strange...I feel sorry for Iris that she's being treated like an object for the royal family(╯°Д °)╯╧ I may come back and read this again in the future...