Why are characters being perceived differently for doing the same things?!?!

Okay so after a few events and seeing reactions, I wanted to just bring something up that was brought to my attention (and passionately talked about by Lucie - making me just as interested as her haha).

... and that is, the way characters have been perceived differently for doing similar things.

A short while ago there was drama between Sophie, Aaron and Elliot as Sophie was spending a lot of time with Aaron (staying at his house etc...) while she was still in a relationship with Elliot.

It was clear what she was doing was wrong and she rightly got a lot of negative feedback for it.

However, I realised... where was the negative feedback for Aaron?

Why did Aaron get away with it, while people viewed Sophie as being wrong?

Why is Sophie's behaviour a disgrace and the way she treated Elliot so bad... what about Aaron?

He did wrong too. So why does nobody have any negative opinions on Aaron for the way he acted?
It was a two way thing, yet most readers and characters in the book just put the blame on Sophie.

(this isn't me trying to have a go at anyone, it was just something both me and Lucie noticed and thought it was interesting... everyone views things differently and I find it intriguing. If you have a reason for the way you judged the matter and feel like you want to argue back, go head! I'm quite interested to hear).

Maybe you didn't realise you did it?

or maybe you have a logical reason?

It's just interesting to us why all blame was put on one individual while the others got away with it like he did nothing.

Does it come down to gender? And what is seen as 'normal' and 'accepted' for one but not the other.

or is it the fact that Sophie was the one in the relationship, therefore it was her responsibility to be the sensible one?