Herpes confusion Help!

So long story short my brother and his friends got pretty drunk about a week ago .. they invited an old friend over... well waking up the next day was pretty blurry and he almost is 100% sure something happened between him and his friend ... she was not there but they were talking on the phone talking about the night and made a comment well it’s not like you have herpes ... (not sure on the full conversation) and she said actually I do I have been on medication for 4 years now ... my brother is freaking out he asked her if they slept together and she told him no but something tells him she’s lying as to now she’s MIA and won’t answer calls or texts ... he went and got test 5 days later and both came out negative for hsv1 and hsv2... I’ve been trying to keep him calm be recently read that it can take as long as 6 months to even get antibodies through a blood test and without an outbreak it can be unnoticed... for ladies that this has happened to help me help him make the best choice as I know he tested to soon... he said he was going to test again June 29 that gives him 30 days in ... would that be accurate?? Or should he wait longer ?