But maybe there was a third reason why Lena wasn't demanding for Kara to tell the truth about her identity. Maybe this reason was because it harkened back to something in Lena's own distant past. Of a different nature, perhaps, but still very much the same underneath...
"Why are you telling me this like I don't already know?" Lex teased after Lena had finished coming out to him.
"Wh-what? What do you mean?" Lena tilted her head, genuinely confused. How had he already-?
"Isn't it obvious?" Lex laughed again. Lena could only shake her head, a sinking feeling growing in the pit of her stomach. "Oh, Lena, baby sister, it was always so painfully obvious! I've known for years that you were gay!"
"But how could you possibly-?" Lena simply could not understand how Lex had managed to figure out her sexuality before she had. This was the first time she'd ever even said words like this aloud, yet here Lex was, claiming to have known her secret all along, even before she had even known that there was a secret she'd been keeping.
"Oh, Lena, Lena, Lena," Lex continued to shake his head in fond amusement. "I've known about this for a long time coming. You aren't exactly subtle about your fondness for women and your disdain for me, after all. You only ever look at, talk about, or flirt with girls. I have yet to hear you say anything about a boy. It's been so painfully obvious to me, Lena! I can't believe you thought you needed to come out at all! I've known for quite awhile now, and so have mother and father!" Lex added. That was when the pit in Lena's stomach threatened to swallow her up.
"They do?" she squeaked. She felt herself grow pale and when she spoke again, her voice had been humiliatingly small.
"Duh!" Lex rolled his eyes with a laugh. He seemed totally unaware as to how uncomfortable this conversation was making Lena.
"Then why didn't they-?" Lena began timidly.
"Ever say anything about it?" Lex finished. Lena could only nod, her brain refusing to find the words she needed to speak. "It's because father said that you needed to discover it on your own time and mother honestly didn't care enough to say anything. I actually wanted to ask, but father told me not to. He said not to bring it up until you said something first," Lex explained.
Just for a moment, of flash of annoyance glimmered in Lex's eyes, but Lena totally missed it, still fretting over what he had just said. So, her coming out hadn't really been a coming out at all because Lex had already known... Actually, scratch that! Everyone knew! And Lena had only intended upon telling Lex! But no, Lionel and Lillian knew too, and Lena hadn't even known... She was sure the shame was going to eat her alive! She hadn't really ever had her own choice in this matter, had she? All along, the cat had been out of the bag. And Lex still didn't seem to realize how embarrassed this conversation was making Lena feel...
From then on, Lena had been insecure about her sexuality, but it was not for the reason one might think. While her family was supportive enough, or just didn't care enough to complain, Lena began to feel embarrassed and ashamed that it had been so obvious to everyone for so long. She wasn't embarrassed that she was queer, she was embarrassed that it had been "so painfully obvious". Lex's words, though entirely well-meant and playful, had planted seeds of doubt into Lena's mind and it didn't take long for them to bloom.
Silly as it sounded, hearing that everyone had known about Lena's sexuality made her feel very self-conscious because she felt like her thunder had been stolen from her. What was supposed to have been a big moment of self-discovery, and her own choice, was ruined by the fact that her own treacherous body had outed her before her mind ever had the chance to fully process the way she felt, let alone come to the decision to talk about it! What was supposed to have been a moment of trust, and of confessing only to Lex, had turned into the reveal that everyone already knew. It made it seem like she was the kind of idiot-girl who wore her heart on her sleeve.
What's more, as a girl who prided herself upon her cold and unreadable appearance, to hear that there was any aspect of her life that was easily readable was deeply disturbing to her. It made her feel vulnerable and exposed because it was a weak spot she hadn't even realized she'd had! Yet, somehow, everyone else had seen it clear as day, like a big red target painted on her forehead. It made her paranoid about what other secrets she was unwittingly sharing with the world and it made her a bit angry that she wasn't in total control of her life, or the way she presented herself. She had always liked to think she was a controlled person, but Lex's remark about her sexuality proved otherwise. Had she been in total control, her coming out would've been a real coming out, not Lex telling her he and the rest of the family had always known. Lena just hated not being in control, and she hated being ignorant. She hated to think that she was readable, and that she hadn't had her own choice in this matter. All of these goings-ons in her personal life and she hadn't even known! But everyone else had, and before she even had a clue. That was the scary part.
So a large part of Lena's life had, in a way, been stolen from her. She never got to experience a real coming-out. What would've been a stepping-stone in her life's growth was a rug pulled out from underneath her. And what's more, to think that she had been displaying all these little tics and traits all without even realizing it! She'd, in essence, been living a double-life without even knowing! She'd been doing and saying all these things for years without even realizing what they really meant while, all around her, Lionel, Lex and Lillian had long since pieced the puzzle together. They had known that which Lena hadn't even realized that she was doing.
Although it was, externally, a minor event, just one small talk with Lex, it had lasting effect upon Lena's psyche. Lex had done more than alert Lena to the fact that everyone already knew she was lesbian. He'd alerted her to the fact that she had a weak spot, and that she was readable. A despicable and disgraceful trait in a Luthor! From then on, Lena placed a high value in secrecy and privacy and she never liked leaking info or telling private secrets if she could avoid it, and it all stemmed back to one tiny incident in her youth...
Although this was nothing at all like hiding an alter ego, there was enough similarity between her own history of keeping secrets, or having them outed for her against her will, that she could sympathize with why Kara was hiding from her. It hurt her to think that Kara didn't feel comfortable enough with her to tell her, but Lena wasn't going to force her to confess. Lena, herself, had been through that embarrassing nightmare already, and she wasn't going to force Kara to live through it as well. Instead, she would only wait, patiently.
She would wait until the day Kara came to things on her own time and terms and decided that she was ready to tell Lena. This was Kara's journey and Kara's secret, after all. Lena had no right to tell her how to live her life, so instead, she would wait for now, and let things come to fruition on their own times. It was the deepest sign of respect Lena could give a person: autonomy. Lena wasn't just keeping Kara's secret out of kindness, respect or pity, but because she was trying to give Kara the thing that she, herself, had lacked back then. By remaining "blind" to Kara's secret, Lena was giving Kara what she never got to have, and in Lena's eyes, that was one of the highest forms of respect she could give someone. She was giving Kara her own choice.
AN: Unintentional other reason why Lena refuses to call Kara out on being SG. Purely headcanon, and something I randomly came up with while writing the previous chapter, which was originally going to be the only chapter.
I was inspired because I imagined Lena saying to Kara "I knew all along that you were SG, I just wanted you to tell me yourself," and if that doesn't sound like the one friend/relative who says "I always knew you were gay, I was just waiting for you to say it!" then IDK what will. (Sorry, Supercorp head is still on).
But people who have had this experience often say it makes them feel uncomfortable because even though the words are well-meant, they do imply a sense of "I already knew", which can be unnerving to someone who had, before that time, wanted to keep their sexuality secret. The "I already knew" seems to take away the person's control in the coming out process. At least from what I've heard from some of my friends. I can't speak for everyone, though.
But anyway, in short, rambling aside, here's another headcanon about why Lena hasn't said anything about Kara being SG yet.