Cats will un-partner once they have had a kitten, or if they go 11 days without producing a kitten (partnerships only last 11 days.)
If they're set to auto-repartner, then once they have a kitten they will re-partner to each other. If they go 11 days without producing a kitten however, they will un-partner.
If it seems like they are un-partnering before they've had a kitten AND before 11 days is up, then send us a ticket by clicking the "Support" tab up top so we can look into it. Be sure to include the ID#'s of the specific cats affected. Thanks!