Nostalgia: A wistful desire to return in thought or in fact to a former time in one's life, to one's home or homeland, or to one's family and friends; a sentimental yearning for the happiness of a former place or time.
I return to the happiness of summer 2011 in thought all the time. August and September were the happiest months of my life, besides my childhood years... Things went so well then. It's crazy how one person can change your life forever; once someone enters your life they never leave. You'll remember them forever.. unless you have amnesia or something. But still.