I feel like canceling my trip to see my girlfriend.
Why do you want to cancel the trip?
Someone told me that she has herpes.
I understand that her having herpes bothers you, but a ton of people have herpes and it's really not the biggest deal in the world. You shouldn't cancel plans to see your partner because of something currently out of her control.
I'll see what I can do.
When you visit her, you should have a frank conversation about her potentially having herpes. It's important that you discuss sexually transmitted diseases with your partner, so that you both can practice safe sex and support each other emotionally.