Indicates that a bad, negative result has been caused for some reason.
Examples:
- 今年は二月の気温が低かったせいか、桜の開花が例年より遅い。The cherry blossoms bloom later than usual, probably because the temperature in February was low this year.
- ストレスのせいか、最近夜ぐっすり眠れない日が多い。There are many days when I can't sleep well lately, probably because of stress.
- お腹が痛いのはきっと賞味期限が切れた牛乳を飲んだせいだ。My stomach hurts probably because I drank milk that had expired.
- 自分のミスを人のせいにするのはよくないよ。It's not good to blame others for your mistakes.