I was diagnosed with mono. a few months after, i was diagnosed with genital herpes. my boyfriends test came back clean. is it possible that the herpes virus came from the mono virus?

No, but...: Being "diagnosed" with a disease usually means there is a high likelihood of having that disease, but sometimes initial diagnoses are reversed when further testing shows that an alternative diagnosis is more correct. If each person gets the Herpes Type-Specific blood test and the EBV Antibodies Panel blood test done, then there can be more clarity about which virus a person has (HSV1, HSV2, EBV).