
Here’s a short answer: Because of the checks of the nobles and the Grand Duke. In the previous timeline, the Grand Duke was considered to be above the imperial family, and they had lost all of their authority. Emperor Richard (Crown Prince’s father) was in fact placed on the throne by the Grand Duke, so, he was basically a puppet emperor who had to whatever the Grand Duke demanded of him, or there would be consequences. One consequence could be the loss of life. So, Sian (Crown Prince) showing affection to her would put her in danger since she is only a fake Veronica, and the Grand Duke could easily swap her and Veronica once he saw a good chance. That chance was when Ian was born. Ian was born between “Veronica” and Sian, giving the Grand Duke immense power over the imperial family since his family produced an heir.
I thought this was going to be like the abandoned princess, it is not but the ml had his reasons to act cruel to the mc unlike in the abandoned princess the ml treated her harshly and kills her cause he was very much a stupid idiot. Ml had already found out the mc was not the real Veronica and had found it the the real “ Veronica” plans to kill the main character but it was to late to save the mc cause she died and found out immediately that Veronica was actually Veronica and almost killed her or someone like that. But he truly loved the main character, he cried very hard when he found out the mc was dead and I’m pretty sure he almost killed him self after he finds out