Although the formerly engaged couple has been spotted together on multiple occasions in the past month, a source close to Aaron exclusively told E! News that "they are spending time together but not fully back on."
Shailene recently accompanied Aaron to his teammate David Bakhtiari's wedding in Santa Barbara, Calif. on March 5, but it was only to "support him," the source said.
"She's not wearing the engagement ring," the source continued. "They are testing the waters."
During the NFL off-season, Green Bay Packers player Aaron has been using the time away from his team to be with Shailene after announcing their amicable split in February.
The same source told E! News, "Since he's been off they have been able to take some time to work on their relationship and try to figure things out. They are going to continue trying to do that and see what happens."
The quarterback and Big Little Lies actress were engaged for over a year before they eventually called it off, a separate source told E! News at the time.
"They are two very different people," the second source explained in February. "They are both focused on their careers but it took them in separate directions." The second source added that "they remain supportive of one another and on good terms."
Days following their breakup, Aaron showed "#MondayNightGratitude" for Shailene in an Instagram post, in which he wrote to the actress, "Thanks for always having my back, for the incredible kindness you show me and everyone you meet, and for showing me what unconditional love looks like, I love you and am grateful for you."