It's no wonder Nangong Beiying thinks this way. She used to feel very lonely without her parents by her side. Later, after meeting Qin Xue and An Xiaochen, she had some companionship, but then her father sent her to the military, separating them again. Yet, they could still gather from time to time until she was discharged.
Before she came here, she felt she was no longer a lonely person. But now, seeing Qin Xue's child so young, separating and reuniting with her parents repeatedly, she felt that such a life was a torment for both adults and children.
This cycle of constant separation and reunion, then separation again, is something only the children of soldiers experience. Therefore, Nangong Beiying thinks that being an ordinary child would be much easier.