There is a topic that I have been thinking about a lot lately. The basic idea is this: my actions and my choices have the power to influence the happiness of others. This being true, when making a choice that will make others unhappy but which make me happy, what moral responsibility do I have to the other?
I do not believe the answer to the question is none. We do have a responsibility to think of more than just ourselves when we make choices, but what scale do we use to rate our own happiness against the happiness of others? The problem is even harder since we have no accurate system of measuring the happiness of others. We can listen to their reports and monitor their reactions, but like quantum physics, we are studying the results of an effect on the things we can see rather than on the thing we are interested in.
Setting aside this problem there are some things we can safely gauge. First we must gauge how responsible we are for an others happiness. In other words, have we made a commitment to this other person to help them be happy or, on the other hand, to keep them from being sad? To some extent this is part of having a friendship with some one: a responsibility to help them through emotionally hard times and help bring happy times into their lives. This said, while we want our friends to be happy, we also hope that they want us to be happy, a fact that does not balance the scales of responsibility, but makes it harder to read.
In addition to considering how committed we are to another's happiness we should take into consideration the expected duration of the emotional change. How long will our choice make us happy and the other unhappy? Will our choice bring us a moment of happiness while causing months of heartache for another?
The other problem with this topic is this, with what weight do you value your own happiness? If you are one who tends to undervalue yourself it is easy to always strive to make others happy at the expense of yourself, but if you tend to overvalue yourself then you will tend to be less concerned with others happiness; what you feel will be more important. The trick is finding the middle ground of compassion for others while having enough self worth to know the value of your own happiness.