After launching an official app for Windows 8.1 and Windows Phone just last month, it appears that TheChive has been pulled from both stores.
It's unknown why the apps were pulled, but it presumably has something to do with a problem that reared its ugly head shortly after their release in which users reported unresponsive power buttons on their Windows Phone devices after installing the app.
We're not sure when we can expect the apps to return to their respective stores, but we'll keep an eye out and let you know when they do. In the meantime, at least you can turn to unofficial apps to get your Chive on.
Thanks to Jason for the tip!