Complex sentence: Ralph introduces his friend Gerald Brenan to Lytton and Carrington, he is planning to leave for Spain in order to improve his education and strikes a liking to Carrington, which is mutual.
Split into simpler sentences: Ralph introduces his friend Gerald Brenan to Lytton and Carrington. Brenan is planning to leave for Spain in order to improve his education and takes a liking to Carrington, which is mutual.