Breaking up is hard to do. Being constantly reminded of the person who broke your heart can be even harder. Back in the day, things were simpler. All you had to worry about was IRL run-ins, but now there are a thousand online minefields you have to avoid. Sure, you can block them on Facebook and Snapchat, but that won't stop them from popping up on the very last online platform you'd want to see them.
You're not alone in seeing your ex on a dating app
A friend once told me his test of whether he's over an ex is whether it would bother him if they were dating someone else. Under that logic, I've never gotten over anyone in my life. Months and sometimes years after a relationship, my heart rate still accelerates when I see an ex is dating someone new on Facebook. Over a year after I ended one relationship, I found some photos on Facebook of my ex with a woman I didn't recognize. It was like we were still together and he cheated.