I know all of you are mad at the prince. I am also mad at the prince but let as not forget...

If he has really changed then why did it take HER changing for him to change? If she stayed the same do you think he would have changed? HIGHLY unlikely. And do you know where it is also quite common to believe that changing one's own behavior will change the other party's? In an abuser/victim relationship.

If you have read a lot of webtoons like this, For sure you know the butterfly effect. I don't mean to start a fight that's just like one of my many thinking and consideration to what the author may be after for.

And another one do you think the boys will be after her if she didn't change. In the past, they didn't care about her anyway so you see it's the butterfly effect it can change a lot of things. That's all spread love

One of the reason he was mean to her in her past life was because the aristocrats faction made him think that she and her family wanted the throne. But the first change that tia made in this life was to ask to break the engagement, what meant that she didn’t want the throne.
And tia keep doing things that doesn’t add to what the aristocrats that use to influence the prince saying. Like how she is not a cold person anymore or how nice she actually is.
So now that there influence doesn’t work they can’t get close to the prince anymore, what mean they can’t drug him too and that mean the prince can logically look at what happening around him and catch on the aristocrats plans. But, for all of that to happen tia needed to change. Because when she change she didn’t just change her fate, she change the prince fate too because in both life there fate was tied together.
Now he’s a different person just like how tia is a different person. And now that no one can get close, drug or control him he wouldn’t hurt tia.

Finally, someone who understands. Thank you for explaining it better than I did