Removing nuts from diet — need substitutions

I have had an anaphylactic allergy to peanuts and tree nuts all my life. My partner and I started dating a few months ago and recently he’s apparently tried to cut nuts out of his diet for my sake. However, he started experiencing some pretty sharp stomach pain and we realized it’s because he didn’t make up for the nutrients he lost after he stopped eating nuts. Since then I told him to just go back to his usual diet and then not eat nuts if we’re going to see each other, but I know he does eventually want to try to eliminate nuts for the most part.

I have more food allergies which makes this even more complicated, so I recommended he talk to his primary or try to see a dietician if he was serious about it. However we both live in the U.S. and are ballin on a budget so seeing a medical professional isn’t on the table right this moment. Was wondering if folks had any advice on how to replace the nutrients lost from cutting out nuts, while also being mindful of my other allergies?

Removing nuts from diet — need substitutions