Complex sentence: Ivana Trump became a naturalized U.S. citizen in 1988, with Trump at her side; however, by early 1990 Trump's troubled marriage and long-running affair with actress Marla Maples had become tabloid fodder, and the couple divorced in 1991.
Split into simpler sentences: Ivana Trump became a naturalized U.S. citizen in 1988, with Trump at her side. By early 1990 Trump's troubled marriage to Ivana and long-running affair with actress Marla Maples had become tabloid fodder, and the couple divorced in 1991.