Complex sentence: He married the widow of Baron de Marches in 1874, after which his style evolved; departing from the typical subjects of realism, he produced colourful salon paintings and still lifes.
Split into simpler sentences: He married the widow of Baron de Marches in 1874, and his style changed from that time on. Departing from the typical subjects of realism, he produced colourful salon paintings and still lifes.