Potential energy of electric dipole in external electric field $U = -\vec{P} \cdot \vec{E}$. Angle between electric field and electric dipole is $180^{\circ}$. $U = -PE \cos \theta = -PE \cos 180^{\circ} = +PE$. On moving towards right electric field strength decrease therefore potential energy decrease. Net force on electric dipole is towards right and net torque acting on it is zero. So, it will move towards right.