Here is what Debbie Allen said was the real reason behind Lisa leaving Different World below:
“When I first took over the show [Different World] one of the first things I did was meet with Lisa Bonet and she secreted to me that she was pregnant.
She had married Lenny Kravitz and you know…I guess Bill had his feelings about that because he was possessive in a way. I mean they were his on-camera wife and children, but they still were his. I mean the way he was with Phylicia [Rashad] (Debbie’s sister) too, I mean, that’s a whole ‘nother story.
So I said ‘Well Lisa we have to go tell him.’ So I said ‘Honey, put some shoes on, don’t come up there with a bare foot…get your best dress, let’s comb your hair and let’s go up there to see him, let’s tell him together.’ So we got dressed, we went up there and oooh he could see us coming! He saw us a mile away he could see us coming (laughs). And he set there and looked at us and I said ‘Well we have some things that we want to tell you.’ He said, “What is it? Are you pregnant?” And then we were like ‘Oh my God.’ Then he said well what is so different about it? He looked at me, he said, ‘You were pregnant, your sister was pregnant, and so now what?”
And I explained to him how I wanted to use it [the pregnancy] on the show because that would be a great thing. To see a girl who’s [this] upper class kid, having a baby, not married because she didn’t want to be married…and the girls could root for her. I was explaining all that we could do. Well honey I was just blowing smoke and didn’t know it (laughs). He listened to it.
We started talking about stories and then immediately…maybe about two or three weeks later he was like “You know what Debbie? No. She’s pregnant, ‘Denise Huxtable’ is not pregnant, Lisa Bonet is pregnant not Denise. So no…no you can’t have it, no we’re not gonna do it, no.” So he took her back, I was so mad at him, I wanted to take her, but I understand, he just wanted her back. So she left us [the Different World cast] to go back home [to the Huxtable house], she ended up getting married on the show and whatever else happened over there.
Cosby had a vision and I guess it was difficult for him to interrupt his creative vision for something outside of his control. I wish they could have figured out a way to make it work, just like they did when Phylicia Rashad became pregnant, although Bill did blame Phylicia’s then husband Ahmad for ruining the show because he got her pregnant. That was a unique and somewhat odd reaction to her pregnancy, but again, Cosby obviously had a vision in mind and anything external interrupted that for him.
All of these years, we’ve been hearing rumors about Lisa Bonet’s attitude causing tension between her and Bill Cosby and that still may true, but it’s good to get a first hand account from Debbie Allen, as to why she actually disappeared from Different World and ultimately from The Cosby Show.