病(びょう)気(き)の() byoukinoため tame彼(かれ)の() karenoコンサート konsaatoに ni行(い)け()な()か()っ()た() ikenakatta。 I couldn't go to his concert because of illness. Literal Illness [because-のため] his concert [to-に] couldn't-go. Subject is omitted — context implies 'I.' コンサートに行けなかった uses the potential negative of 行く. A personal regret about missing an event due to illness. healthentertainment~のため (because of)potential form (~える/~られる)subject omission
病(びょう)気(き)の() byoukinoため tame彼(かれ)の() karenoコンサート konsaatoに ni行(い)け()な()か()っ()た() ikenakatta。 I couldn't go to his concert because of illness. Literal Illness [because-のため] his concert [to-に] couldn't-go. Subject is omitted — context implies 'I.' コンサートに行けなかった uses the potential negative of 行く. A personal regret about missing an event due to illness. healthentertainment~のため (because of)potential form (~える/~られる)subject omission