>>2994834I feel like you're coming from Life Senjou no Bokura from the wrong angle. You have to embrace vignettey-ness of the manga -- when it comes to vignettey literature the appeal is more in how each little snippet metaphorically and stylistically resonates with the other snippets and builds to a larger thematic whole, rather than following a plot or character development.
The big reoccurring image of the manga is the white line roadmarker, which is how the couple meet in the first place. "Following this line leads me to someone important" thinks the uke in the second chapter — romance is a straight line to each other, then continuing on (apparently) endlessly. The seme also believes in the straight line going to the future, but he thinks the future holds a stable family life and kids and is shocked when the uke quits his stable job for the risky life of the writer. It feels like their lives are going in different directions. First the seme, and then the uke, realizes how silly their old way of looking at relationships is -- at the end of the third chapter the uke follows one last white line on the side of the road, but then stops and cries when he hits the end of the line: he realizes that all straight roads have an end.
The climax of the manga happens in front of the aurora borealis in Alaska, after the couple has spent eight years apart growing and maturing on their own. Their relationship had dissolved in the first place because the seme felt he and the uke were going in different directions, but here is a beautiful image of curly, multidirectional lines that branch off each other: a visual contrast to the straight white line that doomed their relationship. The couple realizes that the "ups and downs" of their relationship are better thought of like waves, coming and going in cycles, and they decide to forgive each other.