Characters like Goro and Ichigo show significant growth by choosing to support Hiro's desire to see Zero Two, despite their own feelings.
Inside the cockpit, Hiro and Zero Two finally share their true feelings, clearing up the misunderstandings regarding their childhood memories. Darling in the FranXX Episode 15
Hiro uses a training unit (with the help of his squadmates) to reach Strelizia. Characters like Goro and Ichigo show significant growth
Zero Two is reassigned to the and sent to the front lines. Darling in the FranXX Episode 15
The aftermath of Zero Two's violent outburst in Episode 14 and her temporary separation from Hiro.