How to disable "Share Wi-Fi password" prompt
This happens in one specific circumstance:


Another device is within bluetooth distance of your Mac and both have Bluetooth on. 
The other device is scanning for Wi-Fi
You and the other person are signed in to iCloud and they are in your contacts. 


You can remove their contact, sign out of iCloud, turn off wireless / Bluetooth or share the password. They could sign out of iCloud, turn off Wireless / Bluetooth. 

https://support.apple.com/guide/mac-help/share-a-wi-fi-password-on-mac-mchlp1179/mac

The share should send the password, but their device isn’t connecting, so escalate your steps or possibly vacate the area?

For iOS removing your contact from their contacts might do the trick as well.

https://support.apple.com/en-us/HT209368

Worst case, your iCloud are not syncing identity records or her device needs other fixes. Tweaking these settings resolves the situation on machines without other problems. 


Why we&#39;re not customer support for [company X or product Y]


If none of these help, working with Apple employees would be needed to look at why you can’t share between your two iCloud accounts. That prompt happens since your recipient keeps asking for the password and can’t share it. Focus on fixing the other machine and account is my advice if I understand your setup.