Complex sentence: He also adored short-story writer Katherine Mansfield and, although his romantic affection for her was not reciprocated, the two maintained a close relationship in person and in letters until her untimely death in 1923.
Split into simpler sentences: He also adored short-story writer Katherine Mansfield. Although his romantic affection for her was not reciprocated, the two maintained a close relationship in person and in letters until her untimely death in 1923.