There is nothing to be mad or annoyed about.However those people are not couples and they most certainly do not understand each other.What makes this manhwa interesting is the presentation of people with mental disorders such as Noah's hypersexuality due to extensive abuse ever since he was a child.(In the latest chapter he just got kidnapped drugged and rapped by an old hag.And his unhealthy coping mechanism is to hook up with the first familiar person he sees in front of him.
Also Nayeon has been a supressed nymphomaniac for years and now she is out of control.
It's not just an adult thing.Not all adults are like that.Only the ones who suffer from the same mental disorders with Noah and Nayeon act like that.
You don't seem to understand at all what is going on in this manhwa.
Lol chapters 62 & 63 makes me say that it's just an adult thing lol i don't know but i'm not getting mad with them or getting annoyed with those 2 couple. They understand each other, they're open and that's what makes this manhwa interesting (▰˘◡˘▰)