Méi néng jiàndào fùqīn zuìhòu yīmiàn, shì tā yīshēng de quēhàn.
Not getting to see his father one last time was the regret of his life.
Tips
usage
缺憾 frames a regret as something objectively missing or imperfect, while 遗憾 (yíhàn) is the more personal, emotional 'I regret it.' A film can have a 缺憾 (a flaw); you yourself feel 遗憾.
