They are very different in meaning. 買うんじゃなかった says the expectation wasn't to buy, which expresses a broken expectation and hints at unexpected remorse for having bought and can be translated to "shouldn't have bought" in some contexts. 買わなかった is a neutral statement of fact.
They are very different in
They are very different in meaning. 買うんじゃなかった says the expectation wasn't to buy, which expresses a broken expectation and hints at unexpected remorse for having bought and can be translated to "shouldn't have bought" in some contexts. 買わなかった is a neutral statement of fact.