Apple watch keeps telling me to update my phone

So i’ve read the post but it was a little bit hard to navigate to the answers and fixes so i’ll ask aswell. My girlfriend has an apple watch that she dosen’t use anymore. She gave it to me, we reset and factory reset the watch, so that i can pair it to my phone. When i try to pair it, it ends up telling me that i need to update the watch, and in order to update the watch i need to update my iphone. So i updated my iphone and it keeps telling me to update my iphone. Can anyone help?