I think it's simpler than that: Felicia just likes sex. As long as the challenges involve sex or sexuality, Felicia can roll with the punches like a champ; as soon as the activities move to something more mundane, she loses interest and becomes far more fragile. Unfortunately for her, Kathleen's the one running the show and Kathleen cares about suffering far more than she cares about sex. You can see this most clearly in the cattleprod game in Chapter 4 Update 2. Without the MC's help, all Felicia can focus on is the discomfort.
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It's only if the MC ignores Kat's order and reminds Felicia that there's still an audience who could be aroused by her performance that she manages to get her head back in the game.
In some ways I think it mirrors her reasons for becoming a Carnation in the first place. There are lots of ways a smart, attractive woman like Felicia could go about building a powerbase separate from her husband, but she chose to join an exclusive underground sex club because wholesale debauchery is what she sees as the perfect intersection of her skills and interests. She thought it would be right in her wheelhouse - and she might well have been right if August or Hana was calling the shots. With Kathleen at the helm, however, it's going to be a constant struggle not to lose her groove.