"Are we also responsible for our children's happiness? Our parent's happiness? Is it fair to blame another person because you are depressed?"

Interesting questions NL. I think we are responsible for raising our children as care-free and loving as possible. So that is a sort of happiness responsibility. If we have done our best raising them, then we have completed our task. Later as adults they have to decide for themselves. As for our parent's happiness? I wish I could say no on that, but I would feel guilty if I didn't try to make my mom happy. I wish I were 'more free' in that respect, but I can't jump over my shadow.

No it's not fair to blame another person if we are depressed. But we do.