Maybe, like Yukino, the story itself can be flawed, we see some things that we don't agree with in the flow of the story, but that's okay. What's important is that we were able to understand the concept that the author was trying to get across, which is growing up and maturing into a better person. Yukino managed to grow up a bit, if not fully, and she will still make mistakes, no doubt about it. However, this time, she won't easily back down because she once again has something to fight for.
When I was reading this, I kept thinking.. 'It's a pretty unrealistic story, but what makes it feel so real?'
//oops