Yes, most likely.
It actually isn't that easy to contract. Even if you were in a relationship with her, had sex with her 203 times a week, and all you did was avoid sex during outbreaks, you'd only have a 4-5% chance of getting it a year.
What kind of blood test did you have done? What kind of test did she have done? What were her results on her test? I ask because there are false positives, and if her result was below a 3.5, or it was an IgM test, she needs to get it confirmed. She may not actually have it.