This pattern is used when you hear about someone's reaction or feeling and you think it's completely understandable. It's similar to saying 'It's no wonder that...' or 'It's only natural that...' in English. The nuance is one of empathy or agreement: you're not just saying something is logical, but that you understand why someone would feel or act that way.

It is often used in response to something that has just been said or observed, and it can sound a bit analytical or formal. You'll see it in written Japanese and in formal speech, but less often in casual conversation. When used with verbs, it tends to follow a past tense or present tense form that describes an action or state that prompts the judgment.

A key point is that the subject of the sentence is usually the person whose reaction is being justified, and the pattern is often used with verbs like 'to get angry' (怒る), 'to worry' (心配する), or 'to be surprised' (驚く). It's a way of saying that their feeling is the natural outcome of the situation.