Complex sentence: By this time George and Maurice had become estranged, mainly because of the unflattering portrait of the latter in "Hail and Farewell" and because of Maurice's active support of the Roman Catholic Church, frequently from estate funds.
Split into simpler sentences: By this time George and Maurice had become estranged, mainly because of an unflattering portrait of the latter which appeared in "Hail and Farewell". Tension also arose as a result of Maurice's active support of the Roman Catholic Church, to whom he frequently made denonations from estate funds.