If your answer is not something along the lines of–because the story would die without it–then you must cut it.
I go through manuscripts multiple times before turning them in. Each time, I mark my favorite passages and favorite scenes. The ones that make me stop and say, "Wow! I love this." I do that because I know that by the third or fourth read I'm very likely going to cut them.
To be a writer, you also have to be part sociopath. Keep the lines you cut as trophies or bury the bodies at the bottom of the ocean, but gut your work ruthlessly.
On February 1 I'm going to unveil a secret project. It's a free serial novel. I'll be releasing 2-4 chapters per month until it's complete (which will likely take through the end of 2012). It's an apocalyptic love story. I'm not going to call it YA. You might, but I won't. The main characters are teenagers though. I also shouldn't call it a love story even though there is love. The one thing I can say for sure is that there is an apocalypse. But not in the way you may think.
In addition to that, I'll be running a mirror image website for writers who are interested in the process. I don't like teaching or preaching or whatever it is I feel like I've been doing on this blog for the last couple of years. Because the truth is that I still struggle as much as the next writer. On this mirror image site, I'll be releasing my rough drafts, character sketches, outlines. So that anyone who is interested will be able to see how I got from my crazy scribblings to my finished page.
So, if you want to watch a sociopath work, check back next week when I'll release more details.