Wait, so assuming Lena did not deduce Supergirl is Kara (big assumption but it makes this headcannon cute) then Lena thinks that Supergirl was with Kara and "getting coffee" at 11 pm at night. What if Lena thinks Supergirl is dating Kara?
If we assume that Lena doesn’t know Kara is Supergirl (lmfao like in what world is that even a possibility but anw) then I honestly have to idea what Lena thinks about Kara and Supergirl like does she think they are just super close friends? bessie mates who happen too look extremely alike? gal pals who “get coffee” at midnight? or maybe my poor daughter is just happy that her only 2 friends in National City get along lol idk