Is it sustainability a good word?

Now a days, the word sustainability sounds great and it is usually related with environmental issues but it does not make it a better word.

If I ask you: - "How do you define the relationship between you and your girlfriend?"
And if the unswer was: - "It is sustainable."

I would be quiet sorry for you.

The truth is that our "relationship" with the environment is so bad that we usually think of it as a good word because the next goal is to make it sustainable.