In the end, Pei Qian confessed to Qin Shaoze why she couldn't wait to want to marry him.
It was her sense of urgency, and her worry that he might disappear from her life.
When Qin Shaoze listened, he finally understood where Pei Qian was coming from. She had once lost his younger brother at an unprecedented moment. And she didn't want to experience such thing again.
She didn't want to have any regrets and wouldn't want to wait for happiness to come. It was better if they were happy at the present moment.
She and Li Junfeng had been dating for years before they got engaged which in the end, didn't turn out well.
There was no point in delaying any further if Pei Qian and Qin Shaoze were going to get married in the future anyway. She didn't want for history to repeat itself.