I found out my girlfriend has mono, what can i do to avoid contracting it?

Already exposed ?: If you had it as a kid (90%) you likely have immunity and don't need to worry. If you were exposed to her saliva within the week before she was diagnosed, you had enough exposure and will just have to wait the 4-6 weeks it incubates to see if you got it. If she's been gone, any exposure over the 3 wks to 3 months of the illness may pass it.