Hey AbuinLA,
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 later
1. 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: Close an app on your iPhone or iPod touch.
How to restart your iPhone X, 11, 12, 13, or later
1. Press and hold either volume button and the side button until the power-off slider appears.
2. Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
3. To turn your device back on, press and hold the side button (on the right side of your iPhone) until you see the Apple logo.
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.
Take care.
