Huo Yuhao knew that the trial was almost over, and if it continued, she would be hurt.
He didn't completely withdraw his spiritual pressure all at once, as that wouldn't be good for Nan Qiuqiu.
He gradually reduced the output of spiritual pressure, allowing Nan Qiuqiu to slowly adapt. As the pressure decreased, Nan Qiuqiu's mental state began to weaken.
Eventually, when Huo Yuhao had completely retracted his spiritual pressure, she fell to the ground with a "thud".
Huo Yuhao approached her, raising his hand to wipe the sweat from his forehead. It might have seen like he was only using forty percent of his spiritual power at most, but during the past half-hour, he had been carefully controlling his spiritual power, trying to push Nan Qiuqiu to her limit without harming her. This was a significant test of his control. If it were before his soul core fusion, he truly wouldn't have been able to do it.