What got Lena and Kara fighting in the first place? You can say that it was Kara not telling Lena that she was Supergirl, I think that was just the superficial part of it.
Like we get it she was hurt about the ‘betrayal’ and Lena loves being dramatic, we stan her for it though. However I think a big part of it was detroyed in this episode, Lena wholeheartedly thought Kara didn’t saw her as a villain and didn’t mixed her with the Luthors even thought she had the last name.
She was the one person that always believed Lena was good, always. In that regard Supergirl had her own reservations even when she defended her, we all saw the real name scene, while she believed in Lena she was cautious. It hurt not the fact that Kara was Supergirl but the fact that she did in fact, even if it was only a little part of herself, believed Lena could be the same as her family.
That is heartbreaking, Lena has always been basically alone. She doesn’t have anyone, she didn’t have anyone before Kara, no one that believed she was good. The woman has never seen herself as good, or at least good enough. She was raised as the shadow of Lex and as of today still is tainted by her brother. Nothing will be good enough for the world to believe she is good, and Kara did.
That I think was the real issue between them. I’m not excusing Lena for the bullshit she is pulling because you don’t get to blame others for your own actions. She is making the same mistake that the world did with her, blaming Lena for Lex’s actions, Lena blaming Kara for her actions. You don’t justify bad actions you acknowledge them and move forward.
We have yet to see Kara walk to Lena as Kara, not Supergirl, that is a problem. Supergirl is and has always been National City’s hero. Lena’s hero is Kara, she is the one that told her she was good, that she was enough, that she was better. She is the one Lena relied on, not Supergirl.
Maybe we are finally ending the queer bating and killing all the development Lena has made as a character making her an actual villain. At this point it wouldn’t surprise me.