I get what you're saying... but I think he didn't really treat her like crap... he didn't cheat, didn't force her to take contraceptives, didn't humiliate her (not on purpose at least), didn't break the engagement nor really abandon her. He did seem to be less emotionally invested or not love her as much... but that was from mc POV... he never stopped trying to find her father and he did try to help and protect her his own way. Tbh it wasn't just miscommunication but difference in views and attitude. And even accepting breaking up was due to him respecting her wishes and not lack of love... honestly yeah his persistence can be seen as yffy... but at the same time... that's what mc wanted no? For him to be willing to do these kind of emotional driven actions for her instead of keeping his composure and dealing with it logically like he was doing at the start.
I actually hate this running after the wife after treating her like crap trope... I usually get frustrated because the mc's are usually better off alone or with someone else... and I still dislike this one a bit... the doc and princess are a more interesting couple to me... but I don't hate this ml... they could've solved things by talking and some therapy...

This had a lot of potential. It started out like okay as angst. And I was happy she followed through and left. But when the duke FOLLOWED HER, and wouldn’t leave her alone, continuously stuck his nose in thing to intentionally manipulate and make things harder for her, I was just fed tf up. Not only does she sternly tell
Him to go away, HE HASNT APOLOGIZED ORRR GROVELED in any shape or form. He’s just pushed his way into her life again after treating her like absolute shit. I managed to get through 41 chapters before deciding to give this crap a rest. I mean she’s got courage, but she’s dumb. I mean she managed to pay her fathers debt, flip flowers for gold and use that money to expand: but won’t tell the duke to leave her alone?? And then plot armor comes and has a random bandit attack her and lo and behold, guess who breaks down her door for the SECOND TIME, to get in her house because he “panicked”? I mean the whole premise is mid but he genuinely treated her like crap, yes there was miscommunication but the bottom line is when she needed him, he could never show up for her. Dropped.