Complex sentence: Princess Maria Luisa of Bourbon-Parma (17 January 1870--31 January 1899) was the princess-consort of Bulgaria as the first wife of Ferdinand of Bulgaria, the then prince-regnant and Tsar after her death.
Split into simpler sentences: Princess Maria Luisa of Bourbon-Parma (17 January 1870--31 January 1899). She became princess-consort of Bulgaria upon her marriage to Ferdinand of Bulgaria, the then prince-regnant and Tsar after her death.