Two virgins marry (both claim never had any sex or touching below waist) one develops gential warts, does this mean one cheated since it is a std?

?hygiene issue?: Depending on the social environment of each partner, it "could" have been picked up by poorly sanitized, shared personal spaces--such as locker rooms / bathing suits / etc. It is "usually" an std, and it is easily transmissible by sexual contact--does not mean that is the only way. Cannot grant absolution, however, is potential space for explanation.

Probably: But sometimes it is something else. Be sure the woman gets a pap smear. See a dr with experience with these things, confirm the diagnosis, and learn how to respond.

Not necessarily: Usually in this situation someone isn't being truthful. However, some genital HPV infections have mysterious origins and seem not to be sexually acquired. And as I said in reply to your other question, new GWs are rare at your age and apparently you had a negative test for HPV, so I have to wonder if the diagnosis is correct. Talk to your doctor and/or a dermatologist.