Have you ever suddenly stopped talking to someone online or on apps? What happened that made you completely cut contact without telling them why?

I'm seeing a significant amount of posts on /r/gay about how the potential love of their life suddenly stopped talking to them on apps etc, and while I try to offer theoretical reasons (they're no longer interested in you, they hooked up with someone else, they didn't click...etc), I'd love to hear first hand why people don't give a reason when they cut someone out or block them.Think of it creating a compendium of answers to refer people to later on. Many thanks you awesome gays :D