However, Guo Huai was on friendly terms with Empress Yang Yan, whose associates all greatly praised Jia's daughters. Eventually, Emperor Wu agreed, but selected Jia Wu to marry Crown Prince Zhong. When Wu was to wear formal dress to be examined, however, she was too young and too short for the dress, so Jia Nanfeng was chosen. They married in 272, and she was created crown princess. She was 14, and he was 12. She became quickly known for her jealousy, but she established a relationship with the crown prince where he both loved and feared her. For the rest of her life, she would have him firmly in her control. When several of his concubines became pregnant, she killed them herself in fits of jealousy; Emperor Wu was going to depose her, and only intercession by his second wife Empress Yang Zhi (Empress Yang Yan's cousin, whom he married after her death) led to Crown Princess Jia's being spared. When, on one occasion, Wei hinted to Emperor Wu that Crown Prince Zhong was so unintelligent as to be an inappropriate heir, it was Crown Princess Jia who thought of the solution to Emperor Wu's subsequent inquiries of Crown Prince Zhong—having someone else write simple but correct answers to the inquiries, so that Emperor Wu was impressed.