It is said that P(AB)=P(A AND B)/P(B).....(1)
But it is also possible to havr P(AB) =P(A)....(2)
Now all studious people are warned away from this blog.........
Well I feel that above results can be compares to our happiness as dependent on others'(1) and as independent.
If what someone else does affect us in some way then our happiness can and probably will depend on them to some extent ....depending on the importance of the action and our will power.
But if people's actions don't affect then it should NOT affect our happiness. That is just being plain interfering. Its normal and bad but when you are unhappy , it hardly makes you feel better to know about good things in anyone else's life. And if it doesn't then either you are very good or that person means more than happiness to you.
What's the solution? Acknowledge that and make an effort to occupy thoughts by something more fruitful than complaining and fretting. Peace of mind is more important thna happiness. And if you are at peace with yourself then the world doesn't affect you to extreme ends.