Your wife has had inaccurate medical advice about when she might have been infected with HPV (or she misunderstood the doctor). It's pretty
commonCommon cold for HPV-related pap smear abnormalities to appear out of the blue in monogamous couples. The exact explanations are not always clear. However, assuming your sexual history is as you describe, and also assuming your wife has had no other partners since you were married, there are only two possibilities: your wife had a latent infection since before you were married; or you had a latent infection and transmitted it to her.
You're probably never going to know which situation applies in your case. But this is a common situation in completely faithful monogamous couples. Don't go overboard on the basis of the inaccurate knowledge of a single health care provider.
I hope this helps. Best wishes-- HHH, MD