This pattern conveys that you cannot suppress a feeling or action; it's like saying 'I can't help but...' or 'I find myself...'. It is often used with verbs that describe emotional reactions or strong impulses, such as 泣く (to cry), 笑う (to laugh), or 考える (to think). The nuance is that the feeling is so strong it overcomes your willpower.

The construction is: Verb ない-form + ではいられない. For example, 泣く becomes 泣かないではいられない. Note that the negative form is used, but the meaning is positive: you cannot not do it, so you end up doing it.

This pattern is more common in written language and formal speech. In casual conversation, you might hear ずにはいられない instead, which is slightly more literary. Both are acceptable at N2 level, but be aware of the register.