When Taoyuan became sworn, there was a famous joke that Guan Yu swore an oath to Liu Bei, and Zhang Fei could only confide "Me too" excitedly. Although it is only a trivial picture, it is enough to see Zhang Fei's position among the three. As a big brother, Liu Bei naturally doesn't have to say anything, but Liu Bei won't expect Zhang Fei to give advice, so Zhang Fei is behind Guan Yu. At the same time, Taoyuan Sanjieyi is actually the beginning of the three brothers' intention to conquer the world. Just from Taoyuan, it is doomed that they are all pawns under Liu Bei.
Because Zhang Fei has no culture? Of course not. Liu Bei, Zhang Fei and Guan Yu all took refuge in Cao Cao. During Cao Cao's camp, it was Guan Yu who beheaded Hua Xiong that made Liu Bei highly valued by Cao Cao. Later, Cao Cao's suspicion of Liu Bei deepened, and Liu Bei's three brothers had to flee Cao Cao's camp. It was Guan Yu who sacrificed himself that allowed Liu Bei and Zhang Fei to escape from Cao's camp. This also makes Liu Bei pay more attention to Guan Yu in his heart.
As for Liu Bei crying for Guan Yu, I prefer that Liu Bei not only cries for Guan Yu, but also cries for Jingzhou. The loss of Jingzhou means that he lost a few points on the road to winning the world, and Liu Bei's crying strengthened his soldiers' hatred of Soochow. In fact, Liu Bei's defeat in attacking Dongwu also caused impatience, but it was not only Guan Yu that Liu Bei cried for Guan Yu, but also Jingzhou that Guan Yu lost. As for the death of Zhang Fei, Liu Bei may have anticipated it.