I wish I had had the foresight to say goodbye to him half a year before he died of an illness.
I didn't have the foresight to say goodbye to him half a year before he died of an illness.
ご質問ありがとうございます。
一番目の回答ではwish I hadが「先見の明があってよかったのに」という意味です。2番目の方はただ、「先見の明がなかった」という意味です。
もし私が日本語を読み間違っていて、Zoro様は別れを告げたという意味でしたら、I had the foresight to say goodby to him half a year before he died of an illnessと言えます。
ご参考いただければ幸いです。