Wife now has herpes.

My Wife and I have been married for 25 years, and together for 26 years. A couple years ago, she told me we would have to abstain from sex because she had a sore in her genital area. She went to her Gyn. who confirmed it was genital herpes. We both had to get a blood test, and she came back positive, however I was negative (for g. herpes). Since that time she will get outbreaks every 1-2 months. My question is, is she having an affair? She claims she must have contacted it before we got together. Thanks for all responses.

PB - Seattle