Galecki's and Gilbert’s characters, David and Darlene, played high school loves who eventually had a baby girl and married after Darlene went to college.
The two also dated in real life when they were in their teens, and have remained good friends.
While Gilbert feared Hollywood backlash about her sexuality, he kept her secret.
And his support has continued, which he proved when she contacted him about her plan to discuss their relationship and her personal struggles since coming out in 2010 on "The Talk." "I called him and I just said, 'Is it okay — I'm thinking of talking about this," Gilbert said, adding, "The story sort of starts with you.
So I eventually told him that I thought it was about my sexuality and he was super sweet about it." PHOTOS: Hollywood's gay power couples (He's still super sweet.
If you want, I will be there, and I will hold your hand,'" Gilbert shared."I started dating a woman who was like 18 years older than I was, who was also in the public eye, and it was something that people could have found out about," she revealed. " PHOTOS: TV's best gay and lesbian couples That fear still haunts her."No one knew at the show for years, and Johnny held the secret the whole time, and I just felt like always so scared [about], if it came out, what could happen. "When I talk about my sexuality on the show or in public, I still feel really scared," Gilbert admitted, her voice breaking.Johnny felt badly, I think, and started to take it personally and didn't know what was going on. So I eventually told him that I thought it was about my sexuality and he was super sweet about it. I'm thinking about talking about this and the story kind of starts with you and I have to say that I made out with you and I got depressed. The original series ran for nine seasons on ABC and was widely praised for its portrayal of working class Americans.The series followed the Conner family as they tried to scrape out a living in the fictional town of Lanford, Illinois.Gilbert has appeared on The Simpsons, 24, Will & Grace, Law & Order: Special Victims Unit and Private Practice.Starting in 2004, she had a recurring role as smart but sarcastic medical student Jane Figler on the long-running hospital drama ER; her appearances spanned seasons 11-13.Long before Sara Gilbert joined "The Talk" and Johnny Galecki landed the role of Leonard Hofstadter on "The Big Bang Theory," the two starred side-by-side on the classic TV sitcom "Roseanne." On screen, Gilbert and Galecki's characters dated and eventually married (well, before the series-ender switcheroo that changed all of that). The duo dated, but it didn't go any further than that.That's because, as Gilbert revealed on "The Talk" Thursday morning, it was during her dating days with Galecki when she first discovered she was gay.