Hi There, My Girlfriend Has Been Diagnosed With Molluscum Contagiosum

Hi there, my girlfriend has been diagnosed with Molluscum contagiosum and shes under treatment with cyrotherapy however I do not understand how she got it. We have been together more than a year. We are totally honest and loyal to each other. We are also perfectly healthy. Do you think it is caused by other dormant disease or its just cause of weakened immune system? Thanks