Another aspect could be that Sakura realizes they have grown in different directions. She might have expected a more traditional family life, while Sasuke is still very much caught up in his past traumas and the need for revenge - or in this case, whatever complex motives he has in the fanfiction world. This misalignment of expectations can make her regret the marriage.
In the fanfiction, perhaps Sasuke has a hard time expressing his emotions. Sakura might feel unloved or unappreciated in the marriage. She may have expected more emotional connection and when it doesn't happen, regret sets in.
Chapter 142, "From Enemy to Best Friend?!", is the clearest early answer because it turns Movie Emperor's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The ingredients for making Buddha Jumps Over the Wall were still on...
Chapter 333, "Silver Mine from the Heavens, Yu Yao and Yu Sheng, No Need to Use a Bull Knife to Kill a Chicken", is the clearest early answer because the violence around Han Yue becomes final instead of hypothetical. The setup is Wah..." "Lord, don't rush, there's still another child yet to come,..., but the pressure keeps building through If it weren't for Han Yue stopping him in time, he almost dashed....
Chapter 186, "The Goddess Who Can't Stand the Smell of Pig Manure", is the clearest early answer because it turns Stand's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Seeing Wen Jiaojiao bravely entering the pigsty, Jiang Yan couldn't...
Chapter 284, "You'll Never Get Rid of Me!", is the clearest early answer because it turns Shu Yan's situation into a concrete plot event. It opens with Bai Lu, also an actress, naturally saw through the insincere... and closes on She viciously slapped her phone onto the desk..
Chapter 255, "Daton Festival", is the clearest early answer because it turns Uncle Zhao's situation into a concrete plot event. The chapter turns that into something concrete by moving from Sounds pretty interesting." "I know this one!
Chapter 359, "You Know Who I Am and You Dare Speak to Me Like This?!", is the clearest early answer because it turns Ye Chu's situation into a concrete plot event.
Chapter 92, "Why would a 19-year-old girl read this kind of book?!", is the clearest early answer because it turns West District's situation into a concrete plot event.
Chapter 224, "Won't You Consider Introducing Me?", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Li, ranked number one, was directly taken by the staff to an...
Chapter 335, "Songyang Ridge, Seven Houses Surrender, First Batch of Silver Arrives", is the clearest early answer because it pushes Xu Ning into a new phase or setting. Early on, The name "Songyang Ridge" was not given by Xu Ning; he discovered.... By the end, Ji Yang from Wanlong, representing the Six Families of Songyang....
Chapter 219, "Five Thousand Jin??!!", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Qi Tianyu was somewhat freaking out.