Like, the moment I say to myself "wow, I'm actually happy" I find this need to make myself unhappy. I take everything good in my life, and I find a way to destroy it. I don't know why I do this, I just do. And I'd like to stop, but I don't know how, and I'm not really sure there is a way to stop. I just never feel right when things are actually going good. Something similar happens whenever things become too serious in a relationship. Whenever I see myself falling hard for someone, I freak out. I become the most selfish human being ever, and I run in the opposite direction. I don't think I'm scared of loving someone, because the one thing I want most out of life is to love someone and be loved in return (lol, cliché much?), so I don't understand why this happens. I don't really know where I'm going with all of these. I just want to be happy and not have the desire to ruin it for myself.
This is a common thing, your afrade that everything can't be good in your life. So your natural instint is to distroy what is good to return the world to your normal sort of missirable way. This is odd because this 'way of thinking' usually follows someone whos been in an abusive relationship and I hope that isn't what you've been through. My advice is this: Watch T.V soaps more often, they always have terrible lives and they're always dieing or haveing affares this is to show you when life for you is down there is always someone worse off which I find makes you happyer. You could always try finding good things that make you comfortable start with simple things and work your way up untill you lose the need to distroy all happyness in your life. I'm no exspert of this but I hope I've help somewhat.