It's very dramatic to kill a character suddenly, or allow raeaders to walk in on a cheating husband. Many authors write moments like this in order to provoke an emotional reacion. But your readers aren't going to buy it unless you're easing into it. Abrupt plot turns need to have some backstory. Otherwise, readers just aren't going to care.
You're writing a story about Beatrice and her friend Ursula. But if you kill Beatrice in the first four pages of text, what do I care? I barely had time to meet her before she was suddenly gone. If the remainder of the story is all about Beatrice's loss, I'm not really going to identify because I'm not feeling the pain of that loss. In other words, I won't like that story.
There is merit in slowing down and setting the stage, something that many great writers do before they introduce too much action and plot. Show me some scenes with Beatrice before you take her away. Show her doing something admirable, or intriguing. Get me interested in that character and invested in that character, and then yank the rug out from under my feet. Otherwise, I won't feel the impact of that big moment.
You want to make an impact with your words. Do it properly by setting the stage and letting the reader establish some feelings before you throw them into the meat of the story. Easing into it is a delicate art form, but once mastered you'll be able to jerk those heartstrings much more successfully.