All Hail Lena, Our Benevolent Dictator!!
On her not knowing Kara's 'big secret,' I think Kara should break it to her while talking to her as Supergirl. They're just there chilling in Lena's office after defeating the Big Bad of the week and Supergirl just says, "I have to go get changed, we have that reservation at that new restaurant in an hour!"
And Lena is confused and says, "Wait, I'm going with Kara to try that place out..."
"Well yeah, but I can't go like this," and Kara gestured expansively to her Supergirl outfit. "I need to get changed and find my glasses. You have no idea how many of those I go through in a week!" she quipped with a quirky grin.
Lena is pretty much speechless as Kara flashes two thumbs up. "I'll meet you there. I can't wait to try the sushi!"
Then she turns and launches herself off the balcony.
Left alone, Lena is quickly processing it all, the impossible clashing against the fantastic in her head. She sums up her thoughts with, "What the f-"
Cut to credits.
I know[BLACKOUT] it's the Spiderman: Homecoming[/BLACKOUT] ripoff. Sue me.