There could be a few reasons why your AirPods are not staying paired. One reason could be that Bluetooth is turned off on one or both of your devices. Make sure that both devices have their Bluetooth turned on and try again. Another reason could be that the AirPods need to be reset. To reset your AirPods, go to the Bluetooth settings on your iPhone and find the AirPods in the list of devices. Tap the "i" next to the AirPods and then tap "Forget This Device." After forgetting the device, hold down the setup button on the back of the case while the firmware update begins automatically. Once it's done, reconnect your AirPods by putting them back in their case and then opening the lid. The final reason why your AirPods might not be staying paired is that they need to be updated. Connect your AirPods to your iPhone and then go to the Settings app. Tap "General" and then tap "Software Update." If there's an update available for your AirPods, follow the prompts to install it. After the update is installed, try pairing your AirPods again. If you're still having trouble with your AirPods not staying paired, contact Apple Support for further assistance.