Many people are not aware that "cold sores" or "fever blisters" are the symptoms of oral herpes. The virus that causes these sores is extremely closely related to the virus that causes genital herpes. People with oral herpes may unknowingly transmit their cold sores to their partner's genitals during oral sex. The person with cold sores may even unfairly blame their partner for getting infected.
Oral herpes and genital herpes are misleading names. Although HSV-1 usually causes oral herpes and HSV-2 usually causes genital herpes, either virus can infect either location. In fact, there is some evidence that HSV-1 - usually associated with oral herpes - may actually be more infectious than HSV-2. That means that people with cold sores may be at higher risk of transmitting herpes to their partners than people with genital infections, although they probably neither realize it nor worry about it.
If you have recently developed genital herpes, and are dealing with a partner who is upset because they think you have cheated on them when you haven't, it may be a good idea to ask whether they have ever had a cold sore. If so, they could be the source of your genital herpes infection. Even if they have never had a cold sore, if they are asymptomatically infected with oral herpes they may have put you at risk. Herpes and other STDs can be transmitted even by someone who has never had symptoms, which is why conversations about blame are pointless unless both of you were tested before starting your relationship - and even then it can be counterproductive.
There is an unfortunate stigma about genital herpes infection that is not usually present for cold sores, even though the infections are extremely similar. In part this is because many people get cold sores starting in their early childhood, when the virus is transmitted by casual affection from a parent or relative. However, when the same infection becomes associated with sex, people suddenly want to judge it more harshly - no matter how illogical that may be.
Ignorance over the similarities between the two primary herpes viruses means that even those people who have cold sores often stigmatize people with genital herpes and freak out over a partner's genital herpes infection when they have no concerns about their own oral infection. I have gotten several e-mails from people with a history of cold sores who, when they found out that their partner had been recently diagnosed with genital herpes, insisted that their partner must have been cheating on them and became furious or terrified that they might have been exposed to the virus. None of those people realized that they could have been the source of their partner's genital herpes. They were all shocked to learn that cold sores can lead to genital herpes infections when the virus is passed on during unprotected oral sex.
That said, the stigma associated with infection cam make it extremely stressful to be diagnosed with genital herpes - or to be dating someone who is diagnosed with genital herpes. However, it isn't helpful to panic or to judge. Instead, both of you should focus on learning everything you can about the herpes viruses, and doing your best to keep from transmitting them to anyone else. Try to think of the infection as a mild chronic illness. Doing so will make it much easier to live with.
If you do have either cold sores or genital herpes, remember that the risk of transmission to a partner can be reduced by using suppressive therapy and practicing safe sex. Also keep in mind that, although the risk of infection is greatest during or immediately prior to an outbreak, you can still transmit the herpes virus even when no sores are present.