iCloud email error setting up

I purchased a domain for email through iCloud/apple

I created my email starting with [email protected] I then created my partners [email protected] and realised I needed to add to his iPhone not mine so I deleted Adrian from mine. Went to his to add and it won’t allow it.

Cloudflare still thinks [email protected] is in use and will allow me to add again to my phone. But when I delete and try add to his is wont allow it.

Any way of fixing this?