Yes, this is true of hsv1 and 2.
The newer blood tests we have today are very accurate, but no test is 100% accurate.
Perhaps if you tell us what exactly is going on, we can help you find ways to discuss this with your partner.
I also have a journal entry that is specifically about telling partners -
http://www.medhelp.org/user_journals/show/15788 or just click on my name to go to my profile, then click on journals.
Aj