I love how so many people are all "it's a bad end because Youko and Nana didn't end up together", when Youko managed to find love and forgave Nana, which is basically what Nana wanted. When you see her point of view, she's been upset all this time for hurting Youko, not pining for a romantic relationship. Sure, she had feelings on some level but those were pretty much over with in the course of a few minutes. She's even got a potential new love with Satomi, nothing sad about it for either of them.
Like I said before, it's refreshing to see a manga that doesn't treat childhood friends and high school crushes as some sort of destiny, and that it's okay to go find an even more satisfying love if that doesn't work out.