Affleck's getaway with Sexton comes just weeks after a source told ET that Affleck's relationship with Sexton has "been 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."
The source continued, "Shauna has been a strong support for him by attending his family sessions and listening to the advice, but she doesn't seem willing to give him the space he needs to stay in rehab."
"As I’ve had to remind myself, if you have a problem, getting help is a sign of wisdom and strength, not weakness or failure," he wrote in part. "With acceptance and humility, I continue to avail myself with the help of so many people and I am grateful to all those who are there for me. I hope down the road I can offer an example to others who are struggling."
Just one day after his announcement, ET confirmed that Affleck and Garner had finalized their divorce three years after announcing their separation and more than a year after officially filing. The former couple share three children, Violet, 12, Seraphina, 9, and Samuel, 6.
Last month a source told ET that Affleck is "eager to get back to work and he seems to be taking his sobriety more seriously than ever."