Let me just preface by saying it is always a good thing to make others happy. We humans receive this indescribable feeling only obtained when another person's happiness is the result of our own actions. Doing nice things for strangers, helping out a coworker, and uplifting a friend are all things that you can do to make others happy, and I highly encourage them. You should not, however, feel obligated to do any of those things consistently or on a daily basis. The only person that you are obligated to do things for to make happy is yourself. Yes, yourself. Be selfish, because if you try to be someone else's source of joy, they will drain you.
Everyone has had at least one crappy relationship, unfortunately I've had the pleasure of having quite a few. They have all had one consistent theme: it was my duty to keep them happy at all times. It didn't matter if I was upset, if they were in a bad mood I was to ignore my own emotions and uplift them. Trying to make a stubbornly unhappy and pessimistic person happy is exhausting, both mentally and physically. All of these crappy relationships were with guys that deep down either had no intentions of being a happy person or at least never fought for their own happiness. Guys that deep down did not love themselves. They weren't angry at me for not cheering them up, they were angry they needed me to. Maybe they didn't know how to make themselves happy on their own, but that is for them to figure out. That is for them to deal with. It was not my responsibility to perpetually provide them with happiness at my own cost. It is not your responsibility to be happy 100 percent of the time for someone who would never do the same for you. They do not love you, because they do not love themselves. If they did love you, you would not feel obligated to take on this role as their sole caretaker.
It is your responsibility to love yourself. The biggest problem with always trying to keep someone happy is you forget to have your happiness. Someone who truly loves you will allow you to express all of your emotions and not depend on you for their own happiness. You will make them happy and they will make you happy, but they will not expect you to do anything beyond being yourself. As cliche as the saying is, there is a lot of truth to, "you have to love yourself before you can expect anyone to love you."
When I finally decided to let go of this unspoken responsibility to make someone happy 24/7 I found myself to be a much more positive influence in my own life and well being. I have better friends now and am in a much healthier relationship. I know that I can express my emotions freely with them without fear of rejection. But most importantly I know that I make them happy, but that it's not my job to.