When I was going through my (agonizing) breakup, I could never find the right words or explanation for why I couldn’t be/remain friends with my (ex)partner. He had argued that we could, in fact, remain friends after our relationship ended. He even went as far as to say that there was no reason I couldn’t know his new girlfriend and, maybe, hang out with them in the future. ABSURDITY!!!! I was confounded, deeply hurt, and just really blown away! Although there are some people who can be friends with their ex, they are the minority–somewhat of an anomaly.
This link is to an article which features a short animated (very poignant) explanation of why you can’t be friends with your ex. It does an AMAZING job of this! YOU MUST WATCH IT and read the article! (Sorry, But You Can’t ‘Just Be Friends With An Ex.’ Here’s Why.)