The show is challenging to watch not because of any moral disagreement - hello, morally ambiguous protagonists have been beloved in popular media for decades now - The frustration is watching brilliant actors tied to such predictable and two-dimensional characters, with a central conflict that is as old as Cain and Abel.
You get your bad boy with an accent that won't leave the picture, a sassy best friend that saw it all coming that the protagonist won't listen to, a protagonist with a Ph.D. in psychology who can't assess her own emotions, etc. You get the rest. It's great to see Sarah again, but unless you're a diehard L-Word stan like me, I'm pretty sure you're only sticking around for the illicit sex scenes.