Define sync with whom
Maintain a single list of contacts with sync specification.
In each contact, you can specify to which devices it will be synced.
Sync with my phone, not my wife, not my sister.
Sync with my phone, not my wife, with my sister.
Just for those who have (almost) no secrets for their wife :-p
Olivier Cailloux commented
Forgot to mention, this can be done simply by check marks in columns, as many as your account has devices.
Also leave the possibility to sync with nobody, all checkmarks/devices are not sync, so you can keep contacts that you don't need (anymore) in your phone but would like to keep in your 'archives'.