You should, but unfortunately most people don't and they believe they are invincible, which of course leads to people getting infected with STD's.
Get tested, and don't have unprotected sex until you are ready to marry a person. If a guy is presuring you to have unprotected sex with him, he is so not worth it. You are worth being with a guy who treats you with respect.
I agree with many of the above answers, it is not a trust issue, it is common sense: most guys don't get tested for STD's. Men can show no symptoms of having an STD yet they can pass it on to you.