When i watch the Season 7 Dvd Yeasterday i notice that Cliff(Bill Cosby) and Denise(Lisa Bonet) Hardly have any speaking lines with eachother or not as much as Season 6. most of her scenes are with Claire and Martin. and you could feel some Tension there in some of the last few episodes she was in.

Yes, Bill Cosby wasn't happy with Lisa Bonet at all. It ended up with her getting fired.