Is the grass greener on the otherside?

It means that people often think things will improve if they change, simply because they think change will solve their problems. Think of someone near a fence that separates two fields. No matter which side of the fence this person is on, he always thinks the grass is greener on the other side: what he really wants is something different from what he has.

You can hope for change but usually you simply find that the grass is greener on the other side because that's where the "fertilizer" is being dumped.