Love guru JEN offering advice after ELLEN marriage nightmare!

Jennifer Aniston and Portia de Rossi are now real-life best friends – with Jen helping Portia get a grip on her post-rehab life and troubled marriage with Ellen DeGeneres, sources say. 

As The ENQUIRER reported, the “Arrested Development” star, 41, checked into rehab in May because of booze and drugs. The stress nearly destroyed her six-year marriage with DeGeneres, 56, with reports of cheating and vicious shouting matches.

“After Portia got out of rehab, Jen reached out to her and they’ve been in close touch ever since,” said a pal of Aniston, 45. “The joke among Jen’s friends is that she should charge a fee for her counseling. They call her ‘Mama Jen’ because she’s a nurturer and caretaker to everyone.”

Jen, who was front and center at Portia’s birthday, has hooked her up with private yogi Mandy Ingber and also sent her self-help books.

Like Portia, Jen’s also struggling with her relationship with fiancé Justin Theroux, 43, fighting over everything from the screenwriter’s veiny appearance, to her indecision over their wedding.

“Despite being tied up with her own wedding planning and busy career, Jen has been making a point to check in with Portia every day,” said the source. “Jen has listened for hours as Portia poured out her heart over the issues she and Ellen are grappling with, including fighting over whether to have a baby and how to deal with Ellen’s jealousy.”

“Portia confessed to Jen that Ellen is so possessive that she’s even threatened by how close Jen and Portia have gotten!” The source added: “Jen has been an absolute godsend for Portia.”