Unprotected intercourse is fine if she is only infected orally, which it sounds as if she is, as are most people with cold sores.  There is no risk from having intercourse at all and I'm glad that you are aware that oral sex and kissing are risky activities at this time.  I am assuming that when you say you are negative for HSV 1, you mean that you have tested by IgG test and are negative.  It is important to note that this an imperfect test and it misses 30% of HSV 1 infections compared to the gold standard herpes western blot.  I'm not suggesting that you need the blot now, just letting you know about the fallibility  of the test. 

Not everyone understands about the transmission of oral HSV 1 and it's very good that you two seem to have successfully worked out how to manage this.  It is also a possibility that she could take daily antiviral medicine to reduce the frequency of her cold sores if they bother her.  I used to get cold sores, since childhood pretty often. It just wasn't much fun to be lecturing around the country about herpes with a big lesion on my lip!  So I started taking daily antiviral medicine about 10 years ago - I've had the start of two cold sores since then and was able to jump on it right away with a higher dose and even avoid having those proceed to the blister stage.  Anyway, just food for though for you and for her, something to perhaps discuss with her health car provider.

Terri