  We report on exact-diagonalization studies of correlated many-electron states
in the half-filled Landau levels of graphene, including pseudospin (valley)
degeneracy. We demonstrate that the polarized Fermi sea of non-interacting
composite fermions remains stable against a pairing transition in the lowest
two Landau levels. However, it undergoes spontaneous depolarization, which is
unprotected owing to the lack of single-particle pseudospin splitting. These
results suggest the absence of the Pfaffian phase in graphene.
