can you get stds from having unprotected sex with just one person?Watch
1. "Can you get stds from having unprotected sex with just one person?"
Of course you can catch STIs from having sex with just one person. (I know you were not asking this)
2. "If someone doesn't have stds and neither do you, is it still possible to get them?"
No, STI's do not naturally develop/occur within the human body, instead they need to be caught from an external source
(Academically this could be debated and unpacked but it is not relevant in this context... least I'm ducking the question because it's too complex.)
It depends how you define STIs. For example a fugal infection like thrush does naturally occur in the body and could be spread through sexual contact. Further, through poor hygiene and some types of sexual activity (things that expose you to waste material) it's possible to get sick or catch infections - none of these would be classed as STIs though.
"f someone doesn't have stds and neither do you, is it still possible to get them?"
It's theoretically possible to catch some STIs from non-sexual activity - example pricking yourself with a hypodermic needle that has someone's blood who is HIV positive on it. Obviously such situations are highly unlikely to occur.
My question to you would be how do you know if your partner has an STI? For this reason protection is always important, unless you've both shared recent STI test results and are in a monogamous relationship.