Rei discovering the dark side to being a Harem protagonist.
I mean nitpick all you like, I'm just saying there's obvious reasons cheaters in real life don't inform the other party. It's so incredibly stupid. I can only conclude she isn't thinking at all and is running on pure emotion.
You aren't wrong, but I'll see if I can walk you through it because I've seen people do things that would make what she did seem smart in comparison.
She's got three primary drivers feeding her.
First, is she is self-destructive because she is stressed. This is the #2 cause of people utterly and needlessly fucking up their lives, right behind drugs. (And a lot of people turn to drugs because of being stressed out.) She is looking for any escape she can find. She wants to hurt Itsuki, and she also wants to hurt the Her-who-is-Itsuki's wife. So she goes and fucks her friend's husband for temporary stress relief, which hurts Itsuki, and also destroys her as "Itsuki's wife"; she wants to be repulsive to Itsuki so he'll push her away. She also wants a thrill, she wants to feel a rush, get a massive hit of those endorphins to make the stress go away.
"This is all really stupid and requires you to completely ignore the part of your brain thinking more than 18 minutes into the future. Why don't they just leave instead of concocting this retarded scheme to implode the relationship?" you'll say. And you are correct: they just ignore the readily foreseen consequences of their actions, and for various reasons refuse to just break up.
Second, In addition to her self destruction she is also angry and frustrated. Looking for an outlet, she settles on Mahoro and her "perfect life". She gets self-satisfaction by "having one over" on Mahoro, she took her husband, he prefers Rio to her. She's "won".
I have seen probably at least a dozen 10+ year friendships explode because one girl goes after another girl's boyfriend or husband....adn then dumps him within 6-months because it wasn't that she liked the guy, it was that for whatever petty ragebrain reason she wanted to get one over on the other girl. Once they break up, she loses interest in the guy.
(it happens with guys too I know, but I think [or alteast like to believe] I haven't witnessed that from the male end because if someoen is that sort of guy I don't give them the time of day and preemptively exclude them. with women.... the lower head unfortunately gets a vote on what people I interact with.)
Third, she wants Rei and Mahoro to divorce so she can be with Rei and he can rescue her prince-like from her life with Itsuki.
Once again you will think "This is all really stupid and requires you to completely ignore the part of your brain thinking more than 18 minutes into the future.". And once again, you are correct: this is just ignoring the readily foreseen consequences of their actions.
As
@Jatopian says, if they'll cheat with you, they'll cheat on you. But the number of people who refuse to learn this lesson....
So she is stressed and unhappy. She wants to rub Mahoro's face in the fact she's stolen her man, but can't directly. So she leaves the condom. She starts the blog. She is getting off on the THRILL of baiting Mahoro and not getting caught.
he basically knew something wrong just because her wife look brighter than usual.
First everyone complains about husbands neglecting their wives. Now we have Itsuki paying very close attention to his wife mental state, and everyone's still complaining. gawd.
