Complex sentence: C. Dean Andersson is a American writer of fantasy fiction novels since 1981, both under his own name and, in collaboration with his wife Nina Romberg, under the pseudonym Asa Drake.
Split into simpler sentences: C. Dean Andersson is a American writer of fantasy fiction novels since 1981. He is married with the also writer, Nina Romberg, and they wrote in collaboration under the pseudonym of Asa Drake.