i have HSV-2 and my gf doesn't?

i just found out 2 years into a relationship and i have not cheated, not once, with anyone. i got some sores on my penis a couple weeks ago while i was sick and the doctor said it looked like herpes. i never had anything before now, ever but doctor said it can come up after years. I got swabbed and blood tested and both came back positive for HSV-2. GF got tested and is negative. but we have been having sex without condoms for two years, maybe twice a week most times, so like 100s of times over 2 years and she is still negative. she beleives me that i didnt cheat, but i still cant understand how this happened? kind of stressing. 

How did these sores look like? Were they just red pumps, or actual sores with white cloudy liquid in the middle? I’m currently going thru the same thing, where after showering and scrubbing my penis head with bar soap, my skin got irritated and a few red bumps began to grow. So far they’ve stayed the same and small. I’m currently waiting on test results my self. Please reply, thank you.