Complex sentence: In the castle the new king Guido and his jester Gilberto are planning Guido's marriage with Elisa, but she has just lost her father is still mourning; she refuses to marry Guido.
Split into simpler sentences: In the castle the new king Guido and his jester Gilberto is planning the Guidos marriage with Elisa. Elisa that just lost her father is still mourning and refuses to marry Guido.