not that my opinion would change about him but I would really want a in depth POV of Emper...

I think you're looking at it wrong. Navier says it once. Sovieshu was a terrible husband but a good emperor.
I would argue he's not the brightest tool in the shed, but he's never shown to be explicitly bad at being an emperor, though he's an spectacularly shitty person.
As a husband he was awful, even before Trashta. Now he's being a horrible husband to Trashta, not to mention his whole plan of using her as an incubator for his heir.
He does seem to know when he effed up, but he's not clever enough to know how not to repeat mistakes. But all of these issues are related to his personal life. Not him as an emperor, a job that he seems to take seriously. Several people pointed it out and even Heinry's actions where because the western empire was powerful.

He cared for Rashta initially since he firmly believe she was a good person that was wronged. He believe he has the responsibility to protect her after she ended up in bear trap he set so he felt guilty. Like many others he feel for her beauty and naive/ignorant character. He believe that Rashta is pure minded because she is untainted by the court toxicity (something even Navier liked in Rashta. In fact she wasn't against her being around) believing if you're of humble background, you're automatically a person that can't do bad. Rashta is also the exact opposite of Navier. Navier is very stoic and in recent years cold and professional towards him to the point he asked her if she was actually his wife and not a colleague. So Rashta showering him with praise, feeding his sexual needs and making him feel "I'm such a good person ~ I feel so great I'm showering this girl what any person should have" automatically made him love and care for Rashta's. He believe he was doing good. And I sort of agree with him, giving Rashta a taste of what actual life is.

He started falling out of love for Rashta slowly as her mean and cruel side slowly showing. The animal abuse, cutting a maids tongue, cornering Navier in a social humiliation, tossing their own kid on the floor, etc etc... Slowly the image he had of her dies down. Leaving only the image the consequences of her actions made "a terrible woman that abuses people and animals that can't defend themselves from her." Rashta ignoring his warnings/orders and ignoring and hiding away her actions from the nobles assigned to help her was a break of trust for him and it cost him face to.

The whole reason why he has not visited Rashta after the kid was born was bc 1) he didn't trust Rashta with their child 2) Rashta is doing not even the bare minimum of her duty as an empress (which is fair she's not prepared it even interested doing the empress job) this he works double the amount, in fact he's always in his study. 3) he slowly realized the woman he just married and is the mother of her daughter is someone he doesn't know and he believes is actually a monster (animal abuse, tongue cutting, sending assassins... ) since Rashta purposely put on the act of a naive ignorant slave girl.

yeah you're right, I was mixing both up. but im still amazed how people are like that in real life too, like you can be perfect in one important aspect but can't do that for the rest? I would think that would influence all aspects of him, not just being a good emperor but an all overall good person. but I guess not

In the novel there are some parts where we can see what goes through his mind. To be honest, he NEVER loved Rashta, he was charmed by her, he realized that he didn’t have to work to make her happy cuz she was as simple as a slice of bread, a ring and the girl was kissing his feet, contrary to Navier, he didn’t have to make efforts. It’s also important to remember that he wanted a reaction from Navier, he wanted to make her jealous.

He believed Navier to be just like him (personality wise) and an extension of himself (as they grew up together), so that’s why he thought she would guess what he was thinking even without saying a word about the plan. He is aware he is using Rashta and feels kinda guilty, which is why he is so mad at Navier when she puts clear boundaries the moment Rashta arrived at the castle, he is projecting.

About their relationship… we really don’t know why they became so stoic with each other, but I feel people overlook that it was mutual. The first thing we see is him calling Navier “empress”, not wife, Navier or anything loving. He NEVER confessed his feelings for her when they were kids, so she grew up thinking they were partners, more that loving spouses, it was an arranged marriage as himself informed Rashta about. He never tried to change that but expected Navier to know his feelings. The shock for Navier is the betrayal of a best friend and sudden realization that she in fact loved him. She was surprised and hurt when he confessed that he has always been in love with her.

It was pure arrogance, remember when he reverts to his crown prince time, he kind of show us he used to think “I’ll never be like my father

Read the novel.