そんなわけで

that's why

→ そんな
phrase Rare #38,740
that's why Introduces a result or conclusion based on what was just explained; also means “for that reason.”
JA: 電車が止まっていました。そんなわけで、遅刻しました。
EN: The train had stopped. That's why I was late.

そんなわけで私は昨日学校を休んだのです。

That's why I was absent from school yesterday.

そんなわけで、オーストラリアは嫌いだったんだ。

That’s why I hated Australia.

そんなわけで、私は昨日授業に遅れたのです。

That's why I was late for class yesterday.

そんなわけで、彼はほとんど言うことがなかった。

That being the case, he had very little to say.