When your ex is dating someone else
Every single aspect of the relationship is coming to an end.
Deep down inside, you might have had this weird fantasy that you and your ex would get back together one day.
The reasons your ex may care depends on the nature of your relationship as well as other factors, such as his personality and past experiences.
One reason your ex may care if you are dating is because he still holds onto feelings for you.
You might have starred in your own epic romance novel inside of your head, subconsciously convincing yourself that maybe, just maybe, those drunken hook-ups and late-night conversations meant the two of you were holding out for each other in the name of a grand love story.