"Ben is truly dedicated to his sobriety and those around him are celebrating his turnaround," the source says of the 46-year-old actor-director. "He is listening to the counselors and his loved ones and has finally ended his relationship with Shauna. Ben took the initiative to break things off."
The source continues, "This breakup was exactly what Ben's friends had been hoping for because they felt Shauna could lead Ben back into the party world all over again. The counselors told Ben that he shouldn't start a new relationship at this early point in his sobriety, especially with a woman who isn't sober."
"Close friends were honest with him about being in a relationship with someone who was only 22 years old," the source says. "Jen's opinion truly still matters to Ben. Jen tried to be supportive of his relationship with Lindsay [Shookus] but she couldn’t get behind this."
Following the split, Affleck's friends are looking forward to a "fresh start" for the Justice League star.
"At this point, those that love Ben see this as a fresh start. They are planning his long-term treatment and are thrilled that Ben has realized that he needs to put his health first in order to save his own life," the source says. "Ben's real constant throughout this process has been Jen. Despite the fact she went through hell in their marriage, she has stuck by him. Jen wants to ensure Ben has a long, healthy life so he can be there for their children's lives.”
Jennifer Garner Makes First Public Appearance Since Finalizing Divorce From Ben Affleck
Last month, a source told ET that Affleck's then-relationship with Sexton was "challenging for everyone who is trying to help him through this process."
"He has been told to hold off on a relationship... but isn’t heeding that advice. His closest friends hoped he was just dating her and would break it off after going to rehab, but he seems to get closer to her every day," the source said at the time. "The more time Ben seems to spend with Shauna, the more he seems to want to go home."
While Affleck has since split from Sexton, Garner is ready to jump back into the dating game.
"Jen has been a huge support to Ben and an incredibly present mother to their three children, but she realizes she needs more in life," a source says of Garner, who shares three kids -- Violet, 12, Seraphina, 9, and Samuel, 6 -- with Affleck. "While she loves and supports Ben for her children's sake, her marriage has been over for years and she is ready to move on."
"Jen recently began dating and she loves it," adds the source. "She hasn't had anything serious yet, but she's been on several dates."
According to the source, Garner seems to be staying "far away from celebrity dating."
"Her closest friends are in full support of Jen moving on and finding someone special to spend her life with," the source continues. "She truly deserves the very best. After everything Jen's been through, her friends and family are rooting for her to move on and live her life without Ben, and finally she seems 100 percent on board."
Watch the video below for more on Affleck and Garner: