1- Herpes symptoms are different from person to person and if the typical ones are painful blisters, that doesn't mean it has to be like that in every one. I myself have never had a blister but was diagnosed through culture with genital type 1.
2- Herpes test is NOT included in the routine STD tests and you have to ask for the Igg type specific blood test for herpes.
3- Herpes symptoms CAN show up any where in the boxer shorts area. Some people get infected genitally but the symptoms recur on their butt cheek, lower back and ...
4- Stress, anger, heat, sunlight and lots of other things are triggers for the herpes attack but again they vary alot in different people. Some people stress out like crazy but never get outbreaks because of it.
5- The best way of diagnosis is either have the doctor open a blister and swab it (when the symptoms are present) or have the Igg blood test (in the absence of symptoms). Make sure that you and your wife both get tested.
6- Any blister IS not herpes, and there's NO 100% rule for Herpes as it's a sneaky virus and operates differently on people.
Hope this helped, don't hesitate to ask any questions