There is a interpretation of Alex’s characterization that suggests her murder-anyone-who-hurts-Kara mentality would remain consistent, even under that circumstance.
But that being said, and as much as I felt for Kara, I did so LOVE that particular conflict.
The relationships most vulnerable to collapse are those that don’t yet know how they’d react to conflict that calls for one or both parties to confront and resolve the issue at hand. People hurt people. It going to happen in every relationship because none of us are mind-readers and toes will get stepped on, feelings will be hurt, selfishness will flare up. The response to such a conflict is the important part.
I like that Alex messes up. That she’s not perfect, even when it comes to loving Kara. I like that they misstep and hurt each other, because then we get to watch them confront and deal with those issues. We get to watch them prove there really isn’t anything in this world they can’t overcome, nothing that can tear them apart.
Alex can embody the mentality of, “I’ll murder anyone who hurts you,” without being a hypocrite because when she’s the one hurting Kara, she recognizes it and takes those steps to genuinely find a resolution in the aftermath, and she rarely ever hurts Kara the same way twice.
Now. That being said, when people hurt Kara and don’t care about Kara’s genuine feelings enough to resolve the issue, that’s when Alex starts cracking skulls.