First things first, Mari's relationship aside, her betrayal from her best friend is what s...

You know that's utter bullshit. At least he broke up with him. We get he was just as bad but she was but she refuses to admit that she played a part of the situation. She is acutally worse than Junyoung. She almost ruined her brother's relationship and her brother had quit his job because his coworker was messing with her, and she knew that. She's still upset over something that didn't happen.

She has a right to be upset initially but not now. The situation is clear. She's behaving just like the wife said of the man she was cheating with, she's acting like a vitcim. If anyone needs to grow up, it's her.

true

Let's not forget, she lied and hid stuff from her brother just as much as he hid stuff from her, so there we can say at least in that sense she and her brother are even (and that is if we're generous and forget that it was Mari's actions that ruined her brother's job and long-lasting friendship with his boss; her brother's friend was the director of the hospital while her brother, Sihoon, was just another doctor, so it is accurate to say her brother's friend was also her brother's, Sihoon's boss).
As for Mari's friend Junyoung, given it's Mari's fault her friend got bitch-slapped by a complete stranger in chapter 1, and the "betrayal" was only psichological, I'd say they're even:
-Mari: "You slept with the guy you thought that was my boyfriend!"
Junyoung: "Yeah, well ... you got me slapped-stupid by some lady I didn't even know, just because I was your friend!" ┑(￣Д ￣)┍
The reason why people can't stand Mari is because , if there's a saying that goes "Let the person who's free of any guilt throw the first stone", then you can bet that in this context, Mari here would basically be the thick-faced moron that goes and picks up a stone... acting as if the stuff that other people did to her was so much worse than the stuff she did to the other people, that it turns her own faults into practically non-existent. It's that kind of biased, self-serving attitude that makes many readers hate her and it makes her look like an ugly person undeserving of sympathy. So if you're going to stand up for any character in this story, perhaps you should at least wait till she reflects a bit and develops into a more sympathetic character, before deciding she is anything like a real person you'd want to defend.

Comparing a slap to sleeping with someone you think is your best friend's brother is as drastic as drastic gets, and no, the reason people can't stand Mari is because she was seen as a complcation if not an "ice-berg" to their ship, and she will obviously reflect on it, it's what happens in these things, but keep in mind, her best friend feels bad and isn't even trying to speak to her, which, is most likely what she wants. It seems as though she's more upset about that betrayal than anything, along with things that haven't been touched on, if Mari were the main character of this story, she would be sympathized with just as any other character, oh, and as for the bible verse, it was meant to prove that no one is as innocent as they say/ or seem, which contradicts everyone's argument by saying that everyone here is wrong and can't judge the other. Have a nice day.

No one is saying she isn't, she's a child, much like many readers on this site, and it's human nature to victimize yourself for selfish reasons/needs. No one ever said it was okay, and not everyone does it, or know's they're doing it, but it's true. And if anyone were to put themselves in her shoes they would probably understand. She probably still doesn't see what she did as wrong, which isn't okay, and she most likely isn't focusing on that either, her main focus, as all humans do, is on herself, and her 'own problems'. As in the feact, as I said before, that her best friend was under the impression that she was in love with someone, and got involved with him anyway, misunderstanding or not, it's still a betrayal, like giving someone a pill, knowing that it would posion them, but the pill turns out to be a vitamin, not a big deal right? until the person you tried to poison realises you tried to kill them. The person you tried to poison could be a serial killer, ad you could be the best friend. Accepting what they did/ are doing, but choosing to love them anyway, and then betraying them, even if they deserve it, betrayal is betrayal, and that person would feel hurt. Hopefully this messed up explanation helps.

Okay, so she refuses to admit she was wrong, she probably will soon, considering this is a comic, but he also hasn't tried to make amends with her either. That's just like her and the wife, you knew what you were doing and did it anyway, only difference is, this is her best friend, and he did feel bad about it, but has he ever told her that? for all she knows, her best friend betrayed her and doesn't give a damn, the wife was more mature of course, and wasn't connected to Mari in any way, so her betrayal lies with her husband, he's the one that had loyalties to his wife, what Mari did was morally wrong, but the one who truly hurt that woman was her husband whom she would've, under better circumstances, trusted, same goes for Mari, her trust was in her friend, and he broke it, no matter how bad a person may be/ seem, when someone you love, conciously does something that they know will hurt you, it's human nature to be hurt, no? an arsonist may still cry if burnt alive. Soon enough she'll probably come to realise what she did, but as of right now, her attention is on her own hurt. If you killed a man today and then you find out that a love one was murdered, which one would you focus on? Karma may be in play but that doesn't stop the human mind from feeling sorry for oneself, and for anyone to say otherwise, whatever, there are soe things you just can't explain with words because people sympathize with people they choose to, or people they understand, bye now.

Mari is an immature child with a “victim mentality”. Since the wife of the man she’s cheating with decided Mari isn’t worth it, she’s now looking for other ways to feel as though she’s the sad heroine. Have some basic critical thinking, you’re being embarrassing geez.

Thank you. you stated exactly what i was thinking. They have all hurt each other. both bro and sis hurt each other by being in a relationship with the other friend and hiding it from one another. the mc hurt his bf by thinking he was married and with mari and also for breaking up with him without communicating with him or trying to understand him. he typecast him as the bad guy and refuse to see that he wasn't. he hurt mari by being in a relationship with a guy he thought she was in a relationship with. neighter the mc or mari had tried to repair their relationship with each other.

Indeed. Her behaviour potentially broke up a marriage, severed the friendship she had, and made her brother quit his job.... and she doesn't seem to care at all. Obviously all of those characters are responsible for their own response, but it would be naive to not hold Mari accountable to an extent.

Thank you.

Sweetheart, critical thinking? You're not even trying to understand what I'm saying, bye, do enjoy your day though.

You're right, not sure wth Clouds is going on about since what they said has nothing to do with your topic (the topic was the way she's acting towards Junyoung and Sihoon and whether or not it is justifiable, not that "none of what she did is her fault"... Literally no one is trying to discuss your tangent), but yes Mari had every right to be upset. I DON'T think she has the right to CONTINUE going off on people though, at that point she's just being stubborn. She'll realize soon that nothing REALLY happened, she was originally happy at the thought of them together and she cares about them.