A Stark modulated optical pumping spectroscopic technique is applied to study Pr+3 ion pair absorption satellites of a 3H4(Γ1)-1D2(Γ1) (γ=592.5 nm) transition in Pr+3:LaF3. In addition to σ polarized absorption satellites, bulk crystal symmetry forbidden π polarized absorption satellites are observed. We attribute these π polarized absorptions to crystal symmetry breaking lattice distortions in the vicinity of a Pr+3 ion pair. For any Pr+3 ion pair there are two types of transitions from the ground state resulting in a doublet. A σ polarized transition occurs between the mutually coupled Pr+3 ion pair ground state level and the excited symmetric ion pair state. And a π polarized transition connecting the coupled ion pair ground and the excited anti-symmetric state also occurs. NQR spectroscopy is carried out in order to assign the sattelite doublets to specific Pr+3 ion pairs. The differences between π and σ transitions provide a measure of the Pr+3 ion pair coupling strength, and confirm that the strongest ion-ion coupling strength is much larger than that expected from the dipole-dipole interaction alone.