Williams died during World War II and Marion was reunited with Jones, this time in 1957, when she was kidnapped as part of a Soviet plot to find Akator's crystal skull. Afterwards, Marion and Jones finally managed to get married. After the events of In Search of the Lost Ark, Marion and Indiana became engaged. But a week before their wedding, Jones broke off their engagement and ran away.
When Indiana escaped, Harold Oxley stopped talking to him and Marion gave birth to Henry Jones III (or Mutt Williams as he is called in the fourth film) and married Royal Air Force veteran Collin Williams, who later died in combat leaving Oxley to help Marion raise Mutt. This aspect of the Indiana Jones character was never a big part of the series, but it's still a creepy subplot in the series' past. Not only did he leave Marion when she was in love with him, he did it when he was a teenager and he was much older. This doesn't make the dynamic interesting, but rather makes him a villain in his own story.
While In Search of the Lost Ark ended with Marion and Indiana rekindling their romance, Karen Allen didn't return for Indiana Jones and the Temple of Doom (which was technically a prequel) or The Last Crusade. Marion Ravenwood is a main character in the Indiana Jones franchise, who appears as the deuteragonist of In Search of the Lost Ark and the tritagonist of Indiana Jones and the Kingdom of the Crystal Skull.