Thank you for reaching out. I can certainly understand the frustration of your Galaxy active 2 not pairing to your device with the check mark. If your watch will not pair to a phone, or if it randomly disconnects, restart your watch. You should also make sure the Galaxy wearable app is up to date, but it may be necessary to reset the app and unpair your watch. Give this link a try for steps to assist in pairing your watch as well as some of the troubleshooting steps mentioned above: https://www.samsung.com/us/support/troubleshooting/TSG01003238/
If you have tried the troubleshooting steps mentioned above and are still experiencing these symptoms, I would recommend a service repair. In order to set up a service repair, please reach out to our customer service team directly at 1-800-726-7864.