In most Spider - Man novels, Mary Jane is indeed present. She's not just a love interest but also a strong character in her own right. For example, in some novels, she has to deal with the knowledge of Peter's double life as Spider - Man. This creates interesting story arcs as she struggles with the danger that comes with loving a superhero, and also has her own life and goals that she is trying to achieve. Her presence in the novels helps to humanize Peter Parker and makes the story more than just about a superhero's adventures.
In some Spider - Man fanfictions, Mary Jane being pregnant can add a whole new layer of drama. It could mean that Spider - Man has to balance his superhero duties with being a soon - to - be father. Maybe he'll worry about protecting his family more than ever, and there could be new villains who target his unborn child or Mary Jane to get to him.
Spider-Man doesn't kill Mary Jane in the comics. Their storylines are filled with ups and downs, but not that kind of tragic event. Mary Jane is often a supporting and important figure in his life, not a victim of his actions.
In most Spider-Man comic runs, Mary Jane survives. However, there might be alternate universes or special story arcs where her fate varies, but in the main continuity, she lives on.
In some storylines, Mary Jane wasn't killed. But in specific alternate universes or non-canonical tales, her death might have occurred due to various villainous attacks or tragic circumstances.