have second thoughts (セカンド・ソーツ)

Idiom Doubt and Uncertainty

意味

to start having doubts about a decision you have made

下した決定について疑いを持ち始める (kudashita kettei ni tsuite utagai wo mochi hajimeru)

例文

"I'm having second thoughts about buying such an expensive car."

"そんな高い車を買うことにセカンド・ソーツを感じています。" (sonna takai kuruma wo kau koto ni **second thoughts** wo kanjiteimasu)