I have been spoiled on the story. But basically she is a dumb as you think and he does begin to regret marrying her shortly after the story winds itself back to the confrontation that we saw. Because being the empress comes with responsibilities and she's to dumb for the job.
He is a brat who wanted someone to fawn over him. I think like the FL he had been doing what was expected of him his whole life and wanted a little romance. Unlike the FL he has the power to just get another wife or whatever. It could have been any woman who sucked up to him. Honestly I think he was intimidated by how strong and smart the FL is. Maybe since she is such a great empress deep down he knows that he can't measure up.
I am happy that this FL has an out. I could easily see a situation where she is stuck in the kingdom, or she leaves to become a nun, and then the kingdom goes to shit and the emperor comes crawling back. Nope, she is gonna marry someone else. Honestly knowing that she is gonna find a better situation is what is keeping me reading this story.
so basically..... we have a hoe emperor and a trashy concubine. but for real tho. Who the fuck marries someone they met after a month? Like what??????? I think thats way messed up than serving a slave