If you attempt can you??????

someone i know attempted oral with another female but she didnt go all the way she didn't even go down with her full mouth on it but she did put her tongue around his head and he says her mouth was very watery he is scared and doesn't know if he can have an std of not i don't think so bec ause it takes lots of fluid not just a little bit he pulled away quickly cause he was scared is it possible or not cause he is very paranoid?