I want to separate my email from my wife's

I'm not sure how you're setup to get the emails mixed.

The fact that both computers are in the same household is irrelevant - if proximity were the issue, then companies with thousands of desktops in an office environment would have a real problem :)

So the question really is HOW are your emails setup, and how are you using them.

If you each have distinct email addresses, even if they're in the same domain, it should just be a matter of setting up the mail client on each computer to only retrieve one or the other emails.

If, however, you're sharing the same email account, then you're going to have to make a change and give one of you a different account. Without knowing more about how you're setup, it's hard to be more specific.

There are various potential causes. Three possibilities:

If you have signed into your spouse’s email as an additional email account, you’ll have the info separately if selected on one email account, or can be mixed together whrn thr email client is viewing all inboxes.

If you have Apple Intelligence enabled, that completely reorganizes the inbox organization.

And for what is probably most common cause for these cases, if the same Apple Account is used everywhere, you’ll want to switch to your own individual Apple Accounts. That’s discussed here:

• Make sure that each family member has a unique Apple Account - Apple Support
• How to “unshare” an Apple ID - Apple Community