Well, we all get nervous on our first time. We think that we may do something wrong, or whatever. That is normal.
But if you feel VERY nervous, maybe it's a sign that you're not ready. Either with that person, or in general. You should speak to your partner about it.
You should only have sex when you are totally comfortable with the person in question. You should never have sex because you feel you have to.
In all, relax. But don't have sex because you feel you are being pressured to. Do it in your own time, with someone you are comfortable with.
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