To ensure the invite wasn't received, in the Find My app, tap Items. If you do not have see the invite, close the Find My app and then restart the iPhone. Below, we've provided the steps on how to close the app and then restart the iPhone.
iPhone X and later1. From the Home Screen, swipe up from the bottom of the screen and pause in the middle of the screen.2. Swipe right or left to find the app that you want to close. 3. Swipe up on the app's preview to close the app. For future reference, you can also review the steps here: .Steps are also listed here: Restart your iPhone.
Have your wife check for pending invites by following the steps here: Share an AirTag or other item in Find My on iPhone.
If she's not seeing a pending invite or it is showing and you still haven't received it, we recommending contacting Apple Support here: Get Support.