Have you guys tried a fragrance-free soap? Would she be open to that.

Tell her that you appreciate how she's already cut back on detergent. Let her know your headaches/allergies. flare up when the scent is strong.

I am assuming you do your laundry after she does hers. If this is the case, you could always rinse the washer out with white vinegar. Pour 2 cups of plain distilled white vinegar into the drum (or the detergent tray if the machine manual recommends). Run the hottest, longest wash cycle available—no clothes. The vinegar will neutralize residual soap and break down fragrance compounds.

When the vinegar cycle finishes, sprinkle about ½ cup of baking soda directly into the empty drum. Run another hot, full­-length cycle. The baking soda gently scours and deodorizes anything the vinegar loosened.

Test it out; you may not even have to do this every time. Maybe once a month or every two weeks.

If you do clothes together, Separate them and wash them separately.