There was this one time, a few years ago when I heard that my best friend's boyfriend was going to break up with her. They were going out for the night on their "break up date" where he was supposedly going to call it quits, but of course, I couldn't just let my best friend be broken up with. So I followed them to their date to find her and tell her to do it first. But knowing my luck, I bump into them both getting a questioning look from her boyfriend, and a "uhh, what are you doing here?" from my friend. I got her to the bathroom and told her about what was going to happen and told her to do it first, which she agreed to. So I ended up leaving, going back to my house only to get a text from her a half hour later saying "thanks for ruining my relationship. He wasn't going to break up with me." So basically I thought I knew what was going to happen, tried to do something I thought was going to fix it, but yet, made the thing I thought was going to happen actually happen.

This can relate to Oedipus Rex in how the prophecy said Oedipus was going to kill his dad and have sex with his mom. Having the knowledge of the prophecy and what was supposed to happen, and with the preventions of having Oedipus killed, but failing to do so and having him abandoned ultimately led to him unintentionally complete his prophecy. If Oedipus never had known about the prophecy then he quite possibly would have never commit what he had done, just as how my friend wouldn't have broken up with her boyfriend if she hadn't known, but since she had, she did.