But the uke said, he wants a baby.
To respond to 'that', Hyesung was in the throes of passion while he was on heat. You can't really count that as being sane. In his concious mind, he is still denying that Doujin somewhat likes him, and that being together with him is okay (coz of his upbringing and Doujin's wealth). That's after the earth-shattering sex he flees. And had several attempts of running away because maybe in his subconcious mind he's accepted his fate as an omega and that he is bonded with Doujin (which can be hard to accept since he lived his life knowing he was an Alpha, and his father trauma)
But you don't have to take me seriously, this are all my opinion in matching the puzzle that is this manga.
Really, it's hardly a puzzle (I just don't have a better term).
Anyways, the plot is the cliche push and pull but we love it anywayyyys! Why? Because the characters have their own background story that makes their personality. It spiced things up.
That's why, instead of everyone pouring their energy hating on Hyesung. Let's cheer on the artist, scanners and translators to continue giving us many more chapters of this WONDERFUL toon/manga/manhua.
But in the end they end up together.
He didn't want to be pregnant, it was not his choice to take that much responsibility noting from where he is coming from (with family trauma) cut him some slack, okay?
Don't stress yourselves, he may only be experiencing Postpartum Depression.