Separate icloud/apple ID accounts but we've got shared contacts
Both my husband and I have separate icloud accounts, but our contacts are merged. i just started to delete his on my phone and didn't realise but they were simultaneously deleting from his phone too. why is this happening and what can we do to separate them? I can't see how it has happened when we both have our own ID and icloud accounts?
Any suggestions would be gratefully received - thanks!
iPhone XR, iOS 14