The passage of time when you feel like your happiest days have already occurred and your closest relationships have already occurred. I had a glorious childhood, despite having annoying bouts of OCD, and had great times with friends. The last time I remember consistent happiness (lasting longer than a month) was freshman year of Highschool. It was after that when I entered the relationship I am currently in (I'm 20 now) and all of my childhood friends ditched me because I was hanging out with someone else. I have always been a bit easy to pick on due to a lack of assertiveness, so I became their scapegoat. Over the years they have stolen my things, planned to break into my house, vandalized my place and talked behind my back. It is only now, four years after the event, that I have finally let go of that anger and have begun reconneting with a few of them. It has been hard though. I have gone to their parties to try and converse and build bridges again, but it always devolves into drinking fits where they all seem to be destroying themselves on alcohol, speed and narcotics (I don't do these).
Part of me thinks that I have lost my ability to socialize. Part of me thinks that I'm in that subset of society that few want to converse with (the knowledge lover who talks almost solely about what he learns since he has no social experience to recount).
Years into the relationship, I feel like I want to go experiment with other girls. This is super hard for me, because not only do I care for my girlfriend deeply, she is also one of the only close friends I have left. I have tried socializing in college, but the friends I have made so far have been ephemeral and I feel no deep connection. So I find myself in the strangest feeling of wanting to depart, but at the same time wanting nothing more but to continue. The fact that we live together makes things harder.
And amidst all of this, my mom was an alcoholic who mixed booze with sleeping medications and was rarely there through the latter years of high-school. It was only during senior year when we finally got her into rehab and it was only at graduation that I finally felt something and broke down crying. Worse yet, my Dad had been so resentful over the years that he had shut himself in and I felt little personal connection with him. After my Mom sobered up and we tried to connect to him, he denied any shunning of emotion. Devoid of almost all personal connection in my life, I broke down sobbing more than I had ever before.
On top of that, my OCD has come back and since then I have trained myself to never trust my inner voice. Intrusive thoughts batter my mind and make me think I am a million things I am not. As such, I have little confidence and my actions make people question me at times.
On the upside, my grades have never been better and I still have a girlfriend. I'm finally back home, so I can talk to a lot of old friends and feel some humanity. I'm transferring to another state soon in the hopes of finding more friends at another college. I miss getting excited about what I love with other people. In the words of Chris McCandless "happiness is only real when shared".
TL;DR: Had some great friendships and experiences which mostly evaporated with time, parents got divorced, relationship is in limbo, OCD and general social anxiety creating a vacuous void in my heart where happiness once stood.