Those spoilers are from novel updates. All I did is sumerising them.

Also, don't take me wrong, I am only trying to explain the reasons why Tia died in the first timeline, I'm absolutely not trying to defend Ruve but I still want to explain why things happened the way they did in this timeline.

I just want to give the rationale for the actions of the first timeline.

So, when assassins broke in, Jeremiah unconsciously protected Tia with her body, leaving Ruve defenseless. It crushed Ruve's heart to see that Jeremiah didn't consider him like a son. All of this fuelled Ruve's spite against Tia who had everybody's love.

And when they attacked, Jeremiah unconsciously protected Tia with her body, leaving Ruve defenseless. It crushed Ruve's heart to see that Jeremiah didn't consider him like a son. All of this fuelled Ruve's spite against Tia who had everybody's love.

He was also always compared to her and found lacking. Ruve's biological mother was just a servant he didn't love. In addition, Ruve loved Jeremiad and considered her like his mother (his own mother had abandoned him, solding him out to the emperor). His humble origins were in fact the real source of his feeling of inferiority towards Tia.

However, when Jeremiah gets assassinated later on by him, she "happily" gives up her life to protect Tia, while ignoring Ruve (who was also in the same room), so Ruve feels betrayed that Jeremiah didn't care about him at all, which I mean, of course this woman will protect her biological daughter over the unrelated prince.

But all of that, 2nd timeline Ruve overcame. 1st timeline Ruve couldn't because Duke Jenna had gotten close to him since childhood. He was the only person who had ever been warm to him, so Ruve trusted him.

Duke Jenna poisoned Ruve's mind against Tia since young, saying she was an ennemy from the faction that wanted to overthrow him, a doll without feelings who didn't even pay respect to her deceased mother (while Ruve still did every year), etc.

On the other hand, Tia is naturally gifted and smart and everyone always says "Tia is so amazing, we love her so much!" Imagine being a young boy, growing up and seeing how everyone, including your own father, loves Tia so much and nobody gives any love to you at all.

Of course he grows to resent Tia.

As I explained earlier, Ruve grew up without any love. His father thought he needed to be harsh with him because "you need to raise a cub like a lion, if you want him to be a lion" while at the same time being sweet and doting on Tia.

He gives her all the love he has and gives zero love to his son.

He does love prince Ruve a lot, but was perhaps misguided.

The aristocrats all have harsh expectations on Ruve to grow up to be intelligent, rational, capable so everyone is always telling him "You need to stop whining, you need to be better". The reason is because in order to survive as Emperor, you have to be cold, logical, rational, and strong-willed.

Like Jeremiah rushes to Tia and covers Tia with her body, while leaving Ruve to fend for himself against the assassins.

After this, Duke Zena is the only person who shows any "love" to Prince Ruve, which is why he believes anything Zena says.

Zena basically tells Ruve that Tia is an unfeeling, incredibly manipulative and intelligent woman who is out to marry him so she can get more power for her household and the aristocrat faction. Thus Ruve hates Tia even more.

Tia, on the other hand, despite being loved by everyone, also has really harsh expectations put on her and she feels she cannot show any weakness, that she must prove herself to be a capable Empress.

She actually does have trouble expressing her feelings which is why Zena's whole "she has no feelings" rings true to Ruve. However, through her actions, Tia proves that she cares deeply about the Empire, her household, and even Ruve.

However, one day Ji-Eun magically appears and is denoted the "child of god" and the one who is supposed to be empress. Ji-Eun gets to enjoy a life of luxury and wealth, while Tia does all the official Empress duties as the "Queen".

The Empire is thriving and everyone thinks "Life is so good and our Empress is such a wonderful, kind, happy person, while that b***h Tia thinks she's so much better than everyone. She always acting so stuck up."