Complex sentence: That he went back into the United States Navy, and simultaneously took on the role of responsible father, at the end of the show's run was only superficially surprising; his character had been meandering toward that responsibility in small increments for years.
Split into simpler sentences: That he went back into the United States Navy, and simultaneously took on the role of responsible father. By the end of the show's run this was only marginally surprising as his character had been meandering toward that role in small increments for years.