Normally after a relationship ends abruptly without any explanation or simply confusion, it is normal for one to want closure in order to move on. Closure allows the ex to know why the relationship ended the way it did.
What puzzles me is why does a person need closure if you are sleeping with someone else? Isn’t that closure? Why does it matter why you broke up? Being sexually active or dating someone else puts your closure at a void. Once you interact with someone else there’s no need for closure. You have to simply move on.
Closure is honestly overrated. Let’s say you do get closure, what are you going to do with that. Oh let me guess, you can finally move on with your life. Closure is sometimes an excuse for a person to get close to someone they once loved to see if they still have a chance. No one wants closure from someone they can’t stand to be around, so why push the issue?
Life is too short to dwell on what could have been. If the relationship was meant to be, then they’ll come back around but don’t force something that’s not there. You don’t want to hurt yourself more or cause confusion.