Definition
This idiom expresses the idea that other people's situations always seem better than one's own, although this may not be the reality.
She always complains about her job, thinking others' are more interesting. She doesn't realize how good she has it; the grass is always greener on the other side.
My friend always thinks that other people’s lives are more exciting, but he doesn't see that they also struggle. It's a classic case of the grass is always greener on the other side.
He quit his stable job to start his own business, but it didn't go as planned. He then realized that the grass isn't always greener on the other side, and he should've valued what he had.