My wife's iCloud account is somehow locked with mine. How to separate us.

You must be sharing an Apple ID. You should both have your own Apple ID’s. You can set up Family Sharing so that you can avoid this behavior. Your wife will need to set up her own Apple ID. Apple recommends that everyone have their own ID so that data, texts, calls, etc., are not shared and kept private for each individual.

When you use Family Sharing, you can share purchases, a calendar, photo album, reminders, your location and subscriptions if you choose to share all or any or those items.

Set up Family Sharing - Apple Support