The beloved TV mum, who recently broke her silence about her abusive marriage to actor David Birney, never let on there were problems at home - but Gross always knew there was something wrong; he just couldn't put his finger on it.
And it took a backstage breakdown for him to realise the extent of her private woes.
Gross joined Baxter on the Oprah show and recalled the day she "started to go".
He said, "One thing led to another and she wasn't stopping crying... and she said over and over again, 'I'm so afraid'... I didn't know what that meant at the time."
Baxter broke down and held her hands up to her face and Gross had to fight back tears as he embraced his former castmate.
He added, "My impulse was to say, 'You're coming home with me...'"
The actress sobbed, "I was afraid of him (Birney) coming back. It was so peaceful (without him)."
Baxter's three kids, who were in the audience, also broke down as they watched their mum try to compose herself.
Gross picked up the story and revealed he always thought his TV wife and her real husband had the perfect marriage.
He added, "They were the poster child of a marriage that was going well... I didn't notice because you (Baxter) kept her mouth shut."
The actor also confessed he had "no idea" his co-star had a drink problem.
The couple's TV son Michael J. Fox revealed on a video he recorded for the Oprah special that he knew there was something wrong with his castmate.
He recalled, "What I noticed with Meredith's drinking was there was another reason underneath it; there was a sadness underneath it. You could tell that something was troubling her... It was the red flag. I think she was having problems with David and that's (drinking) how it manifested itself."