Heisenberg Uncertainty Principle

You can't get the position and speed of an electron without altering the stats (http://en.wikipedia.org/wiki/Uncertainty_principle)

That sometimes happens in human relationships. You can't always ask to somebody or speak about a problem with that person, and don't expect to change his behaviour.

For instance: imagine that your mate has a behavior you don't like. Maybe the way he/she laughs. If you talk to him/her, he/she could try to stop laughing in that way to please you. But that could make your mate unhappy, because had to change the way he/she it for you.

Does our happiness deserve to change other people?
Does a relationship deserve to be broken when you feel you need to change your mate's personality?

As usually in life, you can't answer yes or no. It depends of the circumstances.