It's not bad form at all! Supportive, involved partners are a beautiful thing.
I am not aware of any contraindications with any supplements while on Rebif. The Supplements and Natural Approach forums might be a good place to post your question as well. Jimmylegs could weigh in, I'm sure! Rebif can elevate liver enzymes in some people, and can deplete platelet counts and the like. So I suppose you might keep in mind the effect that certain supplements might have on such things. With MS in mind, I personally take Omega 3-6-9, vitamin E, vitamin D, and gingko biloba. My conservative neuro urged caution about the gingko because not much is known yet about its properties. Hearing his caution, I don't take much. (I listen to, but don't necessarily obey, my doctors!)
Gather info from the doctors, from good naturopaths, from any resource you can--and then make informed decisions. It takes time and energy to do so, and so it is a wonderful way to help your partner with RRMS out and to express your love.
Best of luck.