"The Summer I Turned Pretty" is a young adult novel written by Jenny Han. The story revolves around a young girl named Isabel "Belly" Conklin and her experiences during a summer spent at her family's beach house, where she reunites with the Fisher brothers, Conrad and Jeremiah, who she has known since childhood.
The development of relationships in a novel is ultimately up to the author's storytelling choices and the direction they want to take the characters. In many young adult novels, childhood friendships can evolve into deeper romantic relationships, but it's also possible for those friendships to remain platonic and evolve into other types of connections.
To find out what happens between Steven, Taylor, and the other characters in the story, I recommend reading "The Summer I Turned Pretty" to see how the author chooses to develop their relationships and the overall narrative. It's the best way to discover the twists and turns of the characters' journeys throughout the novel.