
Wait what. What did she do to be hated and have she engagement canceled? Was she just setup by the heroine and capture targets? If the prince cancels simply because he doesnt like 'strong' women then frames her and demands for her business, he's trash. Sounds like she just dodged a bullet by not having to marry him anymore

Actually that might to be the case, the Heronie has mind controling powers and seems to have used it on the prince to turn against the MC.
Which was rather easy since the prince has deep insecurities.
1.
He's the 2nd son, he wasn't ment to be the heir, his older brother was but with him being the Demon Lord he was thrown out as the heir.
The Prince really had to live up to the expectations of being the next King.
I think the nobles and court didn't think highly of him and probably compared him to his older brother.
2. I think he truly did want to marry our MC in the beginning since he thought they were the same. Two lonely kids with too much expections.
He thought that she would understand him and she did but instead of being his comfort.
She wanted to be his strength.
MC lived up to her expectations and beyond them since she wanted him to see she was his equal and he could LEAN on her.
Which isn't what he wanted, he wanted her to LEAN on him. To make him feel useful but with her cultivating all these skills and being great at them probably made him feel inferior.
Making resentment fester in him.
3. The Heroine probably saw this and used it to make herself appear as the girl he wanted. A damsel in distress who needed a someone to lean on, to save them. She made him feel important.
Along with her mind controling powers twisted the Princes POV of the MC.
To someone who would never understand him
To someone who thought themselves better then him in every way.
With already him feeling a small degree like this was easy for the mind controling to take root without fight.
Which lead to the events in Ch. 1 especially his nasty attitude to the MC
╮( ̄▽ ̄)╭
But I could be wrong so take it as you will.
ಠ_ಠ holy shit, she li you have got some problems