Overall it's pretty good manga. MC was realistic and I could believe in this motivation. ML was OK, but his develop was realistic too. Sex was how and that are switch. Few aspects that was not good is cheating (when ML does is it's bad, when MC it's OK) and not consensual sex (always no no no, but often used in many mangas).

The art is decent . Story is trash. Characters are everywhere. No proper explanation

First of all, the art is nice. And boy, the man are packed, I wonder when do they have time to work out when all they do is sit at work.
Anyway, I don't think I have never seen so many cheating in one manga. And the weridest thing is sometimes they are mad that the other one cheated and sometimes they are not. Looots of double standards I must say. The author must be a newbie, because you can clearly see she went for a different approach at first, wanting the main couple to be a bit more "brutal" and then ed it only occasionally. She even ited it in the closure notes, so yeah xD
To be honest, this really isn't good. It's like a hentai gay porn. There is some plot but eventually, it's all about the sex. Author tires to give us some character development but it's jus so random, their decissions are werid and not really smart. You can enjoy it if you turn off your reality check and conscious.