my apple watch band won't come off on one side

Some people have reported similar issues. Try cleaning the watch & band and see if that helps:

How to clean your Apple Watch - Apple Support

then see:

Change your Apple Watch band - Apple Support

Don't force it. If the above doesn't work, I recommend making an appointment at the Genius Bar in an Apple Store near you and let them look at it:

Genius Bar Reservation and Apple Support Options - Apple