If you've been in a long term, monogamous relationship then both of you have been exposed to the same strain/s ------ so it is fine to keep having sex. You cannot reinfect eachother or cause damage. Using a condom is up to you guys but if long relationship and monogamous then I wouldn't worry about it. My husband and I don't use condoms and I was told last year I have HPV (started with warts/low risk to high risk of vulva area), he has never had any symptoms.