Do we blame other people for our lack of physical health? Then why do we tend to blame others for our mental illness, which is called misery?
Happiness is our own responsibility, just as health is. There is a difference however. Physical health has built-in corrective systems that bring health back on track. But mental health has an destructive system called the mind on one hand and a corrective system called the intellect on the other. The intellect has to manage the emotional mind and bring it back on even keel quickly, so that happiness is restored. That is why, to continue to be happy, our intellect has to be on guard 24x7.
Even when in the grip of emotions, we have to first listen to our intellect.