Where, on her version, do you see "cheating"?
The part where she admits to "flirting" and then describes how her ex was pissed about it.
Unless we make a ridiculous presumption that her ex was just looking for a reason to dump her after choosing to be with her, we can determine that the construct of "cheating" that their relationship had included not being superficially sexually interactive with someone else.
Wait...the only way the conclusion that you, and the person who "translated" the sign is anything but a ridiculous, unwarranted slur, is if you already have the mindset of villainizing anyone who deviates from some puritanical, prudish morality.
Which would be odd, considering that I personally deviate from puritanical, prudish morality on a nearly daily basis.
The mistake I suspect you are making is to begin by treating "cheating" as an objective universal standard. It isn't; each relationship, via its partners, creates the parameters of what is and is not acceptable.
Based on the original lady's admission not only of her ex getting pissed, but her supposed friends finding her actions unacceptable, good ole Occam would lead us to the conclusion that she acted outside of the purview of things her ex would be okay with.
Again, this is unless we want to imagine her ex as just choosing to be with her so that he can dump her at an emotionally fragile moment, and that her friends were secretly in on that wild conspiracy theory as well.
What this blogger did is create some alternate explanation for these events, based on his own sick and twisted imagination. There's no reason for him to believe things went down the way he says they did; it's all just his hatred for women, apparently.
1) I've already pointed out where he filled in the gaps with mere guesses.
2) You're devolving his reasons for suspecting an omission of potentially damning facts from her sign as "hatred for women" is the very same type of act you are accusing him of when you say he was making unfounded presumptions about the in-between info in her story.
As mentioned-via-silence by other posters in this thread, though, this detour of the thread doesn't really deal with the original issues, so I'll let this particular topic be and move on to others.