Cause, With Blame Attached
せいで attributes an unwelcome result to a cause. It is the mirror of おかげで, and it points a finger.
- 事故のせいで遅刻しました。(I was late because of an accident.)
Even where no person is at fault, せいで frames the cause as the culprit.
Attaching It
| Type | Form |
|---|---|
| Verb | 寝坊したせいで |
| い-adjective | 忙しいせいで |
| な-adjective | 下手なせいで |
| Noun | 雨のせいで |
せい as a Noun
せい stands alone, which おかげ also does but you will meet せい this way more often:
- それは私のせいです。(That's my fault.)
- 気のせいだよ。(It's your imagination.)
〜のせいにする means "to pin it on ~": 人のせいにするな。(Don't blame other people.)
Choosing Between the Three
| Pattern | When |
|---|---|
| せいで | bad result, and you want the blame heard |
| おかげで | good result |
| ため | neutral, factual, written register |
A report or an apology usually wants ため, not せいで. Writing 「雪のせいで遅れました」 to a client sounds like you are blaming the weather rather than apologising.