There is only one reason for a person to be happy. It is because what they are doing works!
If you want a happy person to be unhappy you should ask them to change what they are doing.
Then, both of you can share unhappiness.
Note: a relationship is relative to your goal.
When you create a goal for yourself that removes the other person's source of happiness it is time for a rethink of one's goal.
I have been single for about five years and I choose not to have any relationships at all.
Why?
Nobody wants what I want.