I have to cook low protein also. Mr Grumpy is limited to about 60 g of protein a day, so my goal is to make meals where the entree is no more than 25 g of protein and then simply keep track during the day. I also look for low protein snacks for him to have during the day - fresh fruit is great, but sometimes he wants cookies, crackers, jello,etc.
Also, I have found this site to be very helpful, it focuses on issues for people with kidney and other health problems,
http://www.davita.com/index.cfm?spMailingID=5302576&spUserID=MjAyNDYyMjA3MjcS1&spJobID=197926900&spReportId=MTk3OTI2OTAwS0
The amount of protein that your partner can have daily should be your starting point. Remember to keep snacks, beverages such as milk and other things in mind, as they can or do contain protein. Perhaps his doctor's office has a nutritionist you can meet with for some help in planning. I find that I am gravitating to recipes that use a lot of veggies, or I add additional veggies to recipes to make them protein friendly. If I am making a somewhat protein heavy soup, then the entree will be vegetarian.