Here's the lowdown on herpes:
The STI Files: Herpes Simplex
Herpes has to be spread from an infected area of the body and during an infectious period, ie during an outbreak or immediately before one. If your housemate has genital herpes, then keeping away from her genitals during any outbreaks should be sufficient.
As the article says, one in five people in the US in infected with herpes, so treat her the same way you treat any other five people, really, unless you're in a sexual relationship.
Hope this helps,
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