Elegant but pugnacious inequality
If $p=30$, $q=r=5$, and $s=18$, $t=u=1$, then the condition is satisfied, but $p+q+r-2(s+t+u)=0$. Furthermore, for sufficiently small and positive $\epsilon$,
let $p=30$, $q=5$, $r=5$,
and $s=18-6\epsilon$, $t=1+\epsilon$, $u=1$.
Then $\frac{s}{p}+\frac{t}{q}+\frac{u}{r}=1$.
However $$\frac{p+q+r}{2}-s-t-u=5\epsilon,$$ thus
$$\frac{-3}{\frac{p+q+r}{2}-s-t-u} = -\frac{3}{5\epsilon}.$$
If positive $\epsilon$ approaches to $0$, then the above term goes to $-\infty$.
It makes a contradiction.