You can easily do what with custom columns. You already have one, so create a similar one with a different name for your wife. You could also do it with tags. Use a tag with your name or something to identify who has read what.
But, as you are using Kobo devices, are you using my Kobo Utilities plugin to fetch the reading status from the Kobo device? If so, you can define a profile to fetch the readings status into a different set of columns for each of your devices. Then when you plug in each device, it will fetch the status and update the columns.
You might also want to look at the View Manager plugin. This can let you swap between different views of the columns. You can create a view for each of you that only shows your columns.
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