We all have our favorite movies, the ones we can watch again and again without growing bored.
We all have our hate-watches, the movies that are so bad that it's impossible to look away.
Then, there's another category: good movies, but ones that are so emotionally gut-wrenching that they're best watched once, and only once. A recent r/AskReddit thread asked "What movie is so good you'd recommend it to all your friends, but so emotionally traumatic that you'll never watch it again?", and the comments are full of great recommendations.