Out of sight, out of mind 眼不见，心不烦；不看见就忘了。

【例句】

Once she moved away, he forgot all about her. Out of sight, out of mind.
她搬走后，他就把她忘得一干二净。眼不见，心不烦。

When you have a lot of things to do, the ones you can't see tend to be out of mind.
当你有很多事情要做时，那些你看不见的事情往往会被忘记。