I have pityriasis rosea and so does my boyfriend, but apparently it's not contagious. how did we both get it then?

No ,read below: Parents of children with pr typically want information about etiology (not really known), infectivity (thought to be very low), relapse (unusual), and complications or dangers (rare) acute, self-limited, exanthematous skin disease felt most likely to be due to a viral etiology. The rash may persist for two to three months, then gone