Your gynaecologist's advice makes sense. With no new sexual exposure since that one episode eight years ago and a negative pap smear already done, your ongoing risk of a new HPV infection is low, so repeating the pap test on a fixed three year schedule isn't essential for you right now. The HPV vaccine can still protect you against strains you haven't been exposed to, so taking it is worthwhile.
Next Steps
Go ahead with the HPV vaccine your gynaecologist suggested. If you ever become sexually active again, or notice unusual bleeding or discharge, resume routine pap smear screening at that point.
Health Tips
Don't wait for a fixed interval if you notice irregular bleeding, pelvic pain or unusual discharge. See your gynaecologist sooner if that happens.