OK, I quickly found another posting that solved my problem. I went to Mail, Contacts, Calendars in System Pref on my partners Mac and opened a second iCloud account (mine) which only does contacts. Her primary iCloud account continues to do email and calendars. The only minor problem was that as soon as I did this the default was to also add my email and calendars, but after I unchecked those boxes it finally settled down to just doing my contacts.
I lost track of who posted this solution, but thanks in any case.