What is happening to me?

Does it ever feel like you end up doing the very things you dislike in other people? And then you start to dislike yourself for it. All my life I could never stand negativity and cynicism - yet of late I find myself being that way. Am I losing my positivity and innocence? A friend once told me that I look at the world with rose-coloured glasses - but I think I liked being that way. Suddenly I feel like I'm losing that and seeing something entirely different. Pray, why is this happening to me? Is age finally catching up? Is it because I am finally out of the protective world that home was? Or maybe it is just a phase...please let it be just a phase. I don't want to add to the already too big list of cynics in this world.