Maybe you should try reading some slow burns cause that’s how they work. Repeat flashbacks are all just mc’s monologue. We saw the ml talk for like what? One chapter? Yet we all can guess what kind of person ML was. Novels tend to add a lot of details to make them realistic. The webtoon is not leaving anything behind so if a slow burn burns a little too slow for you just let it marinate and come back later to read it.
They're following the novel exactly (which I'm more than happy about considering what just happened to December) -- and in fact this is actually moving faster than the novel, this story is very heavily based on their past and their background in swimming, so you're gonna have those repeated flashbacks, that's just how their relationship really started from that moment, so you might just have to let it marinate cause these chapters are setting up the foundation
Why did they make it a point that there is literally no one else in the facility except for the two of them only for nothing to happen!!!