Watchmen is essentially a story about normal people who only pretend to be heroes, as the word "hero" is one of the last words which can be used to describe them. Throughout the story, the results of each characters flaws, bad choices, and personal demons mingle and merge, creating a tangled web of human imperfection. Despite the fact that these characters are going out in the middle of the night to fight crime, they have their own very real set of problems. In a sense, their being branded as "heroes" is somewhat of a joke (as the Comedian character notes in a flashback, "It's all a joke.")
There's a great moment in the comic (which was unfortunately kind of mangled in the film adaptation,) where Adrian Veidt is reflecting on the choices he's made in sacrificing millions of lives in order to unite two nations on the brink of nuclear war, and he asks Dr. Manhattan, "Did I do the right thing in the end?", to which he resonds, "Nothing ever ends, Adrian. Nothing ever ends."
A lot of things have happened in my life in the last few years which still baffle me when I go back and reflect - in these times, I often feel disconnected from myself, as if I'm an observer of my life rather than a participant (in a way, not unlike Dr. Manhattan.) I tend to try to find narratives and trends in my life and figure out how they might translate to text/film/any other storytelling method - possibly because I've spent too much time living in fantasy worlds? I don't know.
And then I realize - life isn't a narrative. As often as it may seem like there are patterns and structure, I remember what I have believed for so many years: "There's no fate but what we make for ourselves." To suggest that life is a story would imply that our futures our written, which I refuse to accept (well, not completely, at any rate.) Life is really just a huge melting pot of billions of people and their trillions of decisions, made every day, every moment of every person's lives. Time is unstable, making fate virtually impossible. So, when you get right down to it, nothing really ever does end - the world is in constant flux, and we are meant to adapt. Right thing? Wrong thing? We're all going to make both of said decisions at one point or another.
I guess what's most important is that we don't get hung up on what's happened. "Keep moving forward." Yes, we can learn from the past, but the important thing is that we keep going, keep adapting, keep living.
Watchmen has no end, really. No problems are solved - the end of the story implies that the conflict will continue indefinitely, and that the characters are going to keep struggling, whether they want to or not. I suppose that's why this story has resonated with me.