I think at first, people will sympathise with Walt. It's a gradual decline from a depressed unrecognised genius family man with a terminal illness into a conniving sociopath, so it's easier to try and justify Walt's actions because he's got a good reason. It just seems like he's having to turn darker and darker to survive against the shit situations and evil criminals he's found himself embroiled with.

Skyler meanwhile, is out of the loop with all of this. She comes across like a naggy wife who is just a buzzkill, but frankly, that perception is just wacky to me. She cares about her family more than anything, and gets really stressed and confused when Walt grows distant and erratic throughout his cancer progression. Walt Jr starts to rebel a bit, Skyler loses support around the birth of Holly, and she struggles to figure out what's going on. The viewer is innately biased, because they see everything, and have this different perception of Walt. So seeing his wife not support him and just add these superficially perceived Karen complaints to his long list of issues involving lethal drug dealers and million dollar deals, leads to this perception among some people that "Walt isn't being treated fairly". So then someone has to take the blame, regardless of the fact that this situation is only occurring or at least made worse by the fact Walt is misleading the person giving him grief.

Then when she finds out, she becomes self-destructive, tries to save Walt Jr and Holly through a divorce/separation. But covers for Walt to spare the drama and turmoil the family would experience. Walt of course becomes more emboldened and egotistical, and takes it as a personal attack on him to take away his family, his home status quo. So he tries to threaten and stonewall Skyler, and she then resorts to a tit for tat trying to make him want to leave (so that she can save Walt Jr and Holly without having to come clean about the whole meth thing).

And when she finally gets onboard with it (or at least supports Walt), some people attribute it as Skyler being two-faced. Instead of you know, being in too deep in a situation she can't really escape from (the suicide attempt, the heavy smoking, drinking, infidelity with Ted, etc being inadequate) then she has to try and get a handle on the narrative and the laundering side of things to try and damage control before Walt leaves the life of crime one way or another (which is why she's so relieved when Walt says he's out).

She was never a bad character, she was a concerned mother and wife operating with very little information, lies and deceptions from her erratic husband, and struggled to have a solution that wouldn't destroy her life and that of her kids in the process. She made some absolute fuck ups, sure. But everyone did.