Constance is George's obnoxious co-star and Al Zimmer's main squeeze. She's not exactly a good actor, but she gets parts because, ahem, nepotism. She can't stand George's self-important antics and is un-swayed by his charm.
The feelings are mutual—part of the reason George laughs so hard when Zimmer shows him the sound film footage is because it's Constance on screen and she's clearly butchering the role with her awkward and overzealous arm movements.
Constance is also a good case study for the fickle movie biz and the unpredictable rat race of fame. Sure, she's getting work as an actress, but she just doesn't have that "it" girl, star-quality factor that Peppy has in spades.