You´ll get "heat" from four things: chiles, peppercorns, ginger and mustard/horseradish/wasabi. Sounds to me like your other half is allergic to capsaicin, so that means no peppers at all, not even paprika - which is a type of chile.
Peppercorns will provide heat. That includes "false" peppercorns, like Szechuan pepper and Guinea pepper - same effect, different family. Ginger is pleasant and unique.
Mustard/horseradish/wasabi provide heat that tends to go up your nose, unlike chiles and peppercorns, which burn in your mouth and throat. A totally different effect.
The Indian spice mixture garam masala means " mixture of hot spices" - for Indian cuisine, this means peppercorns, cinnamon, cloves and nutmeg. I suppose you could try that.
The only other alternative is to do what I do ( because my wife doesn´t like onions OR anything too hot). One sauce for her, and another for me. OR grab a few green finger chiles and scatter them on your dish.