My take: Nagi takes a liking to Tamaki because she's tall and cool and hot, and realises that Tamaki's friend, Yuu, also feels the same way. Nagi becomes friendly rivals with Yuu, and comes to realise that not only is she cute, she's also funny, dedicated, hardworking, and also a little bit lonely. She meets Tamaki alone, and almost immediately becomes disillusioned, because it turns out that her hot tall butch is also a hot tall player, and she's not as into it as she thought she would be.
She's disappointed, but more than that, she's worried about Yuu, who's invested a hell of a lot more into chasing after Tamaki than Nagi ever did. Yuu knows, though, and doesn't care. She'll work harder to keep Tamaki's attention, if she has to. When Yuu finally runs into Tamaki kissing Yuu, she doesn't care about having "lost" Tamaki, at this point: she just needs to know if this is what Yuu wants, because she's come to care about (and maybe even love) Yuu in a personal way, far outweighing her fleeting, superficial crush on Tamaki. Yuu's smile tells her that this is everything she's ever wanted, and Nagi, who only wants Yuu to be happy, can do nothing but beg Tamaki not to fuck it up.
last edited at Nov 27, 2018 9:25PM