Complex sentence: Rosy falls in love with the local schoolmaster, Charles Shaughnessy (Robert Mitchum), who has come back from a trip to Dublin: she imagines that Shaughnessy will be able to add excitement to her life, but Shaughnessy tries to convince her otherwise.
Split into simpler sentences: Rosy falls in love with the local schoolmaster, Charles Shaughnessy (Robert Mitchum), who has come back from a trip to Dublin. Rosy imagines that Shaughnessy will be able to add excitement to her life, but Shaughnessy tries to convince her otherwise.