Legra

The chasing arc and uke just "its ok" everything when the seme apologizes are so underwhelming

Actually, there were no such feelings. Those cliches surprisingly didn't happen. Kaizen didn't like MC because she was like a doll. Raised like a doll by her father and trained to obey her father. He didn't like it at all. He didn't like the forced relationship between them and if his father died earlier he would have broken up with her quickly.
She always showed affection towards him while he showed little only. Then after their first night he dumped her. He thought she would live well even then but then he heard she was disowned. He tried to send her money but she rejected it then she disappeared. He was so busy as an emperor that eventually he forgot about her.
He doesn't have feelings for her.

He is a fucking asshole.
Anyways, he searched for his ex-wife because of his grandma. The Empress Dowager(grandma) was very close to Astelle(MC) so when Astelle disappeared she was the only one who mourned for Astelle.
The Empress Dowager was actually the onlyheir of a noble of the southern lands but because the Emperor married her, her land became part of the Imperial family since there was no other heir and the Imperial family can only claim that land once she died.
When the Empress Dowager died, she gave out a will. This will can only be opened in the condition that Astelle, the Ex-Empress, agrees to it. But of course Kaizen opened it without waiting for Astelle and only looked for her to make her agree to opening it infront of the public so that Kaizen's actions would be covered up.
When Kaizen saw her again, she was in ragged and shabby clothes. He couldn't believe it since the Astelle he knew was beautiful and elegant, adored in beautiful dressess. And he also saw her with a little boy.
When he asked about the boy, Astelle said the boy was her nephew.