While it sounds juicy, stumbling upon the dark secret of a close friend or family member puts you in an uncomfortable position all around, and can lead to a lot of anxiety.
When secrets are dark and life-altering (or even just supremely embarrassing), it can mess up a relationship to tell someone you discovered what they've been hiding. On the other hand, carrying secret knowledge of a loved one's life can feel like a betrayal in its own way.
In a popular Reddit thread, people anonymously shared the dark secrets of loved ones they've accidentally discovered, and whether they ever plan to confront them.
My roommate freshman year in college was a forever alone type - always tried but things never seemed to work out. One day, I'm chilling on my computer and start getting hungry, so I asked him if he wanted to go get food. He replied "no, guess why?" I guessed he had already eaten, but he surprised me by saying that he had a date with this hot chick from a class of his. So I congratulate him and ask him about her - he describes her as that ideal blonde, big boobs, perky nice sexy girl next door.