Final answer:
Ekwefi's bitterness primarily stems from her unfulfilled desires.
Step-by-step explanation:
Ekwefi's bitterness primarily stems from her unfulfilled desires. In the given passage, it is mentioned that she does not blame others for their good fortune but rather her own evil chi who denies her any. This suggests that she feels a sense of personal resentment and frustration due to her own unfulfilled wishes. This bitterness is reflected in her expression and behavior, making her the only person in the happy company with a cloud on her brow.