A source tells ET the actress has been 'his rock' and will not give up on the father of her children.
Jennifer Garner is feeling at peace.
After driving her estranged husband, Ben Affleck, to rehab on Wednesday, the actress is "relieved" that the father of her three children -- Violet, 12, Seraphina, 9, and Samuel, 6 -- is "in a safe place," a source tells ET.
"This has been a rough few days and [Jennifer] wants nothing more than to feel [Ben] is getting the help that he needs," the source says, adding that Garner has "been Ben's rock" throughout this process. "She is used to putting on a brave face, and handling Ben's addiction, but the process has been very exhausting for her. She won't give up on Ben because he is the father of her kids."
Affleck's return to rehab for a third time comes following the actor's recent outings with 22-year-old Playboy model Shauna Sexton, whom he was casually seeing in the wake of his split with Saturday Night Live producer Lindsay Shookus. But Garner's focus has been on her ex's health and well being, for the sake of their three kids
"Ben trusts Jen entirely and followed Jen's instructions," the source says. "This time he sounded willing and ready on all counts. Friends who saw Ben's rapid decline are breathing a huge sigh of relief. They have high hopes for a recovery."
Hear more on Affleck's history with alcohol addiction in the video below.
Reporting by Adriane Schwartz.