We are not responsible for other people's happiness. Neither is anyone else responsible for ours.
That's a hard won lesson but one that will set us free when we are able to fully grasp it. It allows space to discover what it is that will truly make us happy. What is it that I want to do? What do I need to do to make that happen? I don't have to wait on anyone else to do something for me, I can take the steps toward making it happen.
And when others are unhappy, we don't have to stop what we are doing, what we want to be doing, to do for others what they can and should do for themselves.
Isn't that selfish you might ask. No, it's not. It is self-preserving. When we say we don't do for others what they can do for themselves, we're not talking about abandoning people with their actual needs unmet. We're talking about enabling behaviors that are going to basically cripple them into believing that they actually can't do those things for themselves. We need to exercise our muscles to build them and make us strong. Likewise we need to exercise our "I can do this" muscle to make us know we can take care of ourselves.
There is a very big difference between care taking and care giving, and sometimes the line between them is very hard to distinguish. It takes work and practice to recognize the subtle differences, but we can learn to do it. Autopilot is not our friend, however. Let us not think we can learn to use the tools and then never update our skills. New circumstances, new experiences, new people, changes - they can cause us to get lax in using our tools. One day at a time, we need to keep our tools sharp so we can use them without harming ourselves or others.
Today, I will keep in mind that I am not responsible for other people's happiness. I can and may contribute to their well being and their happiness, but I am not responsible for it. I will keep in mind that I am responsible for my own happiness. I am responsible for my own life and my own choices. What is it that I want to do? What is it that I need to do to take responsibility for my life and my happiness? Then I will start doing those things, one next right thing at a time.