They have spent months brushing off rumours that they are heading for divorce, but now Ellen DeGeneres and Portia De Rossi's marriage is back in the papers.

According to In Touch Magazine, the couple's marital woes have led to De Rossi secretly checking into rehab for drugs and alcohol abuse.

An insider claims that the pair are constantly fighting and their relationship is blighted with jealously and lies. It was recently reported that the Arrested Development actress was envious of DeGeneres' close friendship with Modern Family actress Sofia Vergara.

"Ellen is domineering and Portia is passive. Ellen always calls the shots, and Portia never complains," the source told In Touch.

Things allegedly came to a head this week when De Rossi finally sought professional help at a Malibu facility following their latest showdown.

"She felt like a prisoner in her own home. She went from sipping white wine occasionally to drinking at least a bottle or more a day and topping it off with a pill," the insider continued.

"It got to the point where she was out of it four nights a week.

"They've had vicious shouting matches -- with both of them yelling cruel, soul-crushing put-downs that they both deeply regretted."

Although DeGeneres has denied that there are cracks in their six-year marriage, the writing has allegedly been on the wall for months.

"Portia hadn't been happy for a while and was drinking and isolating [herself], and Ellen confronted her," the source said.

"Portia lost it and blamed Ellen for driving her to drink because of her controlling ways and said she wasn't in love with her anymore. Ellen was crushed and screamed at Portia to get out."

Neither DeGeneres or De Rossi have commented on the rehab reports.