This pattern conveys a sense of 'cannot afford to be doing (something)' or 'cannot stay in a state of (verb)'. It's often used when there is an urgent need to act or a change of situation requires immediate action. The nuance is that continuing the previous action or state is no longer possible or reasonable. For instance, if you're waiting for someone but are late, you might say you can't afford to wait any longer.

It is formed by taking the て-form of a verb, adding は, and then the negative potential form of いる, which is いられない. So the structure is Vて + は + いられない. In casual speech, the は is often omitted, making it Vて+いられない, but the standard form includes は. This pattern is used in situations where there is an external pressure or internal feeling that makes continuing impossible. It's similar to 'cannot keep doing' or 'cannot afford to stay'.

Note that this pattern is relatively formal and appears more in written language or serious speech. In casual conversation, you might hear it, but it carries a weighty tone, so it's not for light topics.