At the end of the day, he's only 19, and pregnant by someone he has known for around a month, no support system, and now financially dependent on a stranger, who he is biologically tied to due to the omegaverse logic, but who he doesn't yet have an emotional attachment to. Dojin too, has struggled with this, but at the end of the day, he has greater security than Hye-sung. Hye-sung's behaviour is understandable, but the plot is playing up certain more serious aspects as being comedy, which is maybe why people aren't sympathising, which isn't really a fair judgement. I guess those who hate on Hye-sung, just want a neat plot, where the tiny little "uke" falls into the arms of their older wealthy saviour "seme", forgiving any past wrongs, and ignoring their valid concerns.
People who hate the Hyesung need to get over themselves. He’s had a traumatic experience which obviously makes him want to distant from Dojin as he’s an Alpha. Obviously he’ll come at a crossroad with Dojin and the baby but right now he’s an immature person dealing with a mature situation immaturely and that’s okay. Not all ukes have to be perfect or accepting of their situation they’re experiencing