you're responsible for your own happiness. Even if someone brings you down, you can choose to not let it affect you as greatly. You cant blame someone for your happiness. no-one can MAKE you anything, you make yourself happy or unhappy.
It ought to be ourselves that are responsible for our own happiness, but more often than not, we blame others for our unhappiness, and that is a wicked cop out.
You are responsible for your own happiness. No one else can claim responsibility for your happiness. At the end of the day, only YOU can decide whether or not you wish to be happy.
There's a good study on happiness on TED (ideas worth spreading)