Typical plotline where the prince breaks off the engagement since he fell in love with a commoner, he is the prince of the kingdom. She goes back to her territory after being forced to meet the commoner who doesn't understand the etiquette, later she goes to the empire and there she met the ML (empires prince) who took her on a date and proposed which she accepted. She then went with her father to a noble who loves books so her and the ML can claim they meet again at that nobles house as justification because ML's previous fiancé "died" (she is not dead, just loved someone else so faked death) and thats basically it for their relationship. In the kingdom her family is the breadbasket that produces high quality wheat, there is an enemy family who has started importing low quality grain thats sold for cheaper (which is what prompted female leads father to go to the empire for trade) and that family has started to create a relationship with the dumbass princes commoner bride to gain more power. There was also some suspicious stuff about how all the other dukes died during a pandemic while their house was the only one that survived. In the most recent chapter (32) the prince just realized that his commoner bride doesn't even know how to write causing him to start the process of realizing the follies of his choices.

Ranato's fiance - who is actually his cousin - is in love with someone else and they were only engaged as basically a Make A Wish for a little girl (the cousin) who was not expected to live past the age of 12. She did, and fell in love with the doctor who cured her - who loved her back, and so she wanted to renounce her nobility and marry the person she actually loved. Renato, being a reasonable person, went along with this and therefore now needed a fiance, and since literally the most competent person on the continent suddenly came free, he asked her. I LOVE Renato - he's a kind and supportive person to the people around him, and his relationships with his aide and brothers are just hilarious. He anticipates that Edward will put all the blame for the broken engagement on Mariabelle, despite her being completely the only innocent party involved, and he moves to block Edward's tr*shing of Mariabelle's reputation with the play by writing and having his own performed. There's a lot of other plot points I would love to discuss - Edward is a complete IDIOT about the people around him, and part of the problem is that he only has yes-men surrounding him, and that lets some terrible influences in. Edward is a completely spoiled brat who does get what is coming to him eventually, and while I feel sorry for Annette - she's a surprisingly sympathetic character, neither a villianess nor a complete angel, just an ordinary person caught up in political games that she is neither prepared for nor willing to be involved in who gets thrown into the deep end and jot supported. Edward makes his own grave, and he's not happy about it but honestly he completely did it to himself. Mariabelle and Renato get to live happily ever after, and he gets to give up his right of succession and get shipped off with Annette, who he no longer is as enamored of as originally. Sucks to be you, buddy - next time try being a decent human being instead of a sinkhole of selfishness!

MC was merely a pawn in those schemes and machinations that happened in the main story. Her engagement was the result of her father's effort to reduce the duke's influence while her broken engagement was the result of the duke's manipulation who wanted to insert his own people to be the crown princess. Poor MC, unaware that she was part of conspiracy. Somehow, she managed to know it in the middle of the story but she was quite calm about it, like she didn't mind at all that she was used by her father. Maybe she thought that it's part of her duty as a noble daughter.

As for ML, he didn't know much about the conspiracy because he was from another kingdom. He only knew few that's related to his kingdom so he hardly helped uncovering the conspiracy.

So in conclusion, MC and ML weren't like the protagonists of the story at all.