It really depends on the type of test given. Some tests don't get an accurate answer. My guess is that if you guys have hooked up (meaning oral, anal or vaginally) you most likely have it. Go back and get another type done, it's really easy to get a false negative. Better to be safe than sorry.
I agree with Twenty1, some symptoms do not show immediately and may take some time, if your partner has that disease , I would really recommend you being tested again and do the right test, some test do not detect certain diseases. A twenty1 said, its better to be safe and sorry.
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