I used to have the occasional look at my ex's page years ago on Bebo (social media site before Facebook), however one day he changed his profile from public to private and then shortly after, someone mentioned that they heard that Bebo had a way someone could see who looked at their pages 😬. I never looked him up again, even on Facebook. I read that Facebook can sometimes suggest people who aren't friends but have looked a your page a few times as friend suggestions...
No matter how bored I get, I'm never risking it lol.