My Apple Watch unpaired itself. When I try to reconnect it gets stuck on verifying data.

Try this;

Press and hold both the side button and Digital Crown for about 10 seconds, then release both buttons when you see the Apple logo.Wait a few seconds, then hold down just the side button for about 20 seconds until the “erase all settings” prompt shows up on the screen, then tap on it, then tap on the green check button.