Cause and reason

～せいで / ～せいか

because of (a bad result); perhaps because of

AI-written, reviewed by AI (ChatGPT)

How to form it

Names the cause of an undesirable result and blames it. With せいか the speaker only guesses that something is the cause.

Always negative in tone. The opposite is おかげで, which credits a good result to its cause.

電車が遅れたせいで、会議に遅刻した。
でんしゃがおくれたせいで、かいぎにちこくした。
Because the train was late, I was late for the meeting.
風邪を引いたせいか、頭が痛い。
かぜをひいたせいか、あたまがいたい。
Perhaps because I caught a cold, my head hurts.
彼のせいで、計画が失敗した。
かれのせいで、けいかくがしっぱいした。
Because of him, the plan failed.

～ばかりに: ばかりに stresses regret over a small cause; せいで simply assigns blame for a bad result.