Responses
I think your idea of the chef is wrong. He does not remember who he slept with that day. Because he can't remember, he thinks he is the father so he wants to take responsibility. So I don't understand what you mean by " if it turns out that he's not the biological father, then he lied and manipulated seonghyun". This was more of a misunderstanding or mistake rather than him lying to be in a relationship with seonghyun.
all characters screams "sus" and i prefer seonghyun to end up alone, being happy on his own
blondie who took interest over bdsm and likes to torture his bed partners clearly not gonna be a good match
the ash wavy guy, is a pushover fuckboy who only wants seonghyun for the sake of his alpha ego
the chef, while he's truly caring and sweet things and so far the better candidate would probably be more toxic than two previous guys because if it turns out that he's not the biological father, then he lied and manipulated seonghyun--maybe to make him symphatize and getting into relationship, ew
last, the businessman guy, idk how he's always having a beef when he met seongyun but bro, if you really like a person then that's not how you behave towards them omg. people gonna defend that he might be a tsundere but alas, the way he talked about omega in front of seonghyun kinda irks me in a way
actually i'm just gonna wait for 10 chapters later if there might development in these guys characters, else bye, i dropped this