This takes place during season 5: Possession.

After Lloyd got possessed by Morro, Adina starts to feel left out of the search by the boys. When she finds out that Nya is going to become the Water Ninja, she feels upset instead of happy, thinking they won't need her in the team anymore. In one of the episodes, Adina and the boys got in a big argument until they said something which (unknowingly and unintentionally) hurts her feelings. When the boys start to leave, Adina yells at them to not expect her to be home when they get back, but they shrug it off. Adina quits the team, despite Wu's protest. During the fight with Morro, the boys thought about what Adina meant what she said at first until they realised in horror of the meaning. One night, Adina feels like giving up until Kai, Cole, Jay and Zane find her and apologise to her. Adina is hesitant at first until she forgives them before breaking down in tears, telling them how she feels (in the episodes). They comfort her, making Adina decide to rejoin the team, much to their happiness.