MimÃ hides and hears Rodolfo telling Marcello why he left Mimi . MimÃ hides and overhears Rodolfo first telling Marcello that he left MimÃ because of her coquettishness , but finally confessing that he fears she is slowly being consumed by a deadly illness ( most likely tuberculosis , known by the catchall name `` consumption '' in the nineteenth century ) . Rodolfo , in his poverty , can do little to help MimÃ and hopes that his pretended unkindness will inspire her to seek another , wealthier suitor ( Marcello , finalmente -- `` Marcello , finally '' ) .