と思ってたよ

I thought (that) …

→ と
phrase Uncommon #18,847
I thought (that) … Casual form of と思っていたよ, used to say that something was your belief or assumption before. The subject is often left unstated.
JA: スロバキア出身だと思ってたよ。
EN: I thought you were from Slovakia.

自分は医者になるものだと思ってたよ。

I always thought I was going to become a doctor.

そんなことだと思ってたよ。

I had a feeling it was something like that.

今日はお休みなんだと思ってたよ。

I thought you had the day off today.

フランス語は話せないんだと思ってたよ。

I thought you couldn't speak French.

大丈夫だと思ってたよ。

I thought it would be okay.

おまえはもっと賢い子だと思ってたよ

I thought you were smarter than this.

— ライフ・イズ・ビューティフル (1997)

あんたは死んだと思ってたよ

I thought you were dead.

— レザボア・ドッグス (1992)

「スロバキア出身だと思ってたよ」「スロベニアだよ」

“I thought you were from Slovakia.” “Slovenia.”

お前は離婚したいものだと思ってたよ。

I thought you wanted a divorce.

それはトムのだと思ってたよ。

I thought that was Tom's.

トムはここに住んでると思ってたよ。

I thought Tom lived here.

今週はオーストラリアにいるんだと思ってたよ。

I thought you were in Australia this week.