Love4cats is right, there really is no right or wrong diet. You and your new wife will soon learn there is a lot of trial and error. Some foods she will be able to tolerate, others she won't. Some people will even tell you that she could potentially eat whatever she wants because food has no effect on UC symptoms.
Sometimes when I know something wonky is going on with my bowels, I will change to a low residue diet (a quick Google search will help you learn more about
this). I find it tends to give my bowels a bit of a break. Others don't find this type of diet helpful at all.
I have some idea of what your wife is presently going through. I just graduated from nursing school last month and stress is my big "flare factor" too. I wish you both all the best, and don't become too discouraged if certain things you try don't work out.