An oral herpes sore can heal
within 7-10 days, give or take
, with no treatment. Some may take a
little longer. If it was her first one, and she is newly infected, it could take 2-3 weeks, easily. So yes, if it was an oral herpes outbreak, it could be completely gone by now.
If it was a pimple, or something else, it could also be completely gone by now, too.
It sounds like there is some serious miscommunication happening with you and your gf. Are you being honest with her?