Maybe yes, if you unreflectively act to promote your own enjoyment and to avoid unpleasantness for yourself. But this condition may not be fulfilled. One example is that of a person who has worked hard to become someone who takes deep pleasure in the (morally appropriate) happiness of others. Philosophers as different as Aristotle and Kant agree that we can and ought to promote such a disposition in ourselves -- Aristotle because he believed this to be a necessary element of true virtue, Kant because he believed this would avoid temptations that could lead the agent to fail in her duties. Another example is that of a person who finds that helping others is what she most enjoys doing, but who also reflects on this enjoyment and conscientiously approves of it in moral terms. Had she found that sadistic conduct is what she most enjoys, she would have restrained herself and tried to change her own desires insofar as possible. In both these case, the enjoyment conferred by the helping act is...

When Mary is depressed, this rubs off on those who are close to her. It casts a shadow over their lives and deprives them of what Mary might otherwise add to their flourishing. Her depression also, and more substantially, blights her own life, makes it less rich, interesting, successful than it would otherwise be. Both points support the conclusion that it is ethically desirable that Mary get over her depression. For her own sake and for the sake of others, Mary ought to do what she can to get over her depression and others should support her effort. This conclusion goes against your hypothesis that Mary should spare her friends the effects of her depression. This on your very plausible assumption that isolating oneself from one's friends has adverse effects on one's depression. Mary needs friends in the state she's in. And, realizing this, her (true) friends wouldn't want her to withdraw. Putting this in terms of the Golden Rule, Mary might ask herself: If a good friend of mine were depressed...