Ok, I grant all of the above, and Faye was my favorite character for literally years ... but I can kinda agree with the OP's sentiment, given some of her decisions affecting significant others. Leaving Marten hanging for so long and then declining, while he was completely polite, generous, nice to her, was kinda unfair, but the punching...! too much, and much too hard - it wasn't freakin' necessary! Someone should've punched her like that, every time she did it to that nice boy who loved her.
and then, after setting ground rules with Sven, that she was gone if he did anyone else, ok, fine, but then when he slid into it in a moment of weakness, it was like the crime of the century, everyone was all trashing him like he'd besmirched and traumatized her beyond belief... whatever trauma she suffered there, was SELF-INFLICTED. And he got treated like shit.
and yes, she has mellowed lately, snark intact, it's like, growth and maturity! Cool! I'm guessing Angus is pretty good for her, with his endless patience. Why isn't she punching him when she inflicted bodily injury unto Marten several times? Hmm? Because it was her own michegas, insecurities, her own shit, right? And it was cartoon funny, like the roadrunner and Charlie Brown and all, it was right for QC, but if I had a friend who did that, I'd say something.