Hi
The behaviour that you described may have been caused by your Apple Watch losing contact with your wrist during your workout, causing it to conclude that it had been removed from your wrist.
During exercise, Apple Watch should be worn snugly on the top of your wrist. Apple suggests that you consider tightening your band before workouts and loosening it again afterwards.
Sensor performance can otherwise be affected by temporary or permanent skin changes, such as by some wrist tattoos.
The behaviour can also be caused by accidental screen interactions, potentially including caused by clothing. To avoid accidental interactions with the screen during workouts - which may include pausing workouts or ending them early - the screen can be locked by following the instructions here:
As you have noted, with the Running Auto Pause option selected, the Workout app on Apple Watch pauses running workouts automatically if you stop running and then resumes when you start moving again. To enable or disable this option:
On your iPhone, in the Watch app, go to: My Watch (tab) > Workout - turn on / off Running Auto Pause.
Apple Watch pausing on workouts
