  Neutron stars are extremely relativistic objects which abound in our universe
and yet are poorly understood, due to the high uncertainty on how matter
behaves in the extreme conditions which prevail in the stellar core. It has
recently been pointed out that the moment of inertia I, the Love number lambda
and the spin-induced quadrupole moment Q of an isolated neutron star, are
related through functions which are practically independent of the equation of
state. These surprising universal I-lambda-Q relations pave the way for a
better understanding of neutron stars, most notably via gravitational-wave
emission. Gravitational-wave observations will probe highly-dynamical binaries
and it is important to understand whether the universality of the I-lambda-Q
relations survives strong-field and finite-size effects. We apply a
Post-Newtonian-Affine approach to model tidal deformations in compact binaries
and show that the I-lambda relation depends on the inspiral frequency, but is
insensitive to the equation of state. We provide a fit for the universal
relation, which is valid up to a gravitational wave frequency of ~900 Hz and
accurate to within a few percent. Our results strengthen the universality of
I-lambda-Q relations, and are relevant for gravitational-wave observations with
advanced ground-based interferometers. We also discuss the possibility of using
the Love-compactness relation to measure the neutron-star radius with an
uncertainty of about 10% or smaller from gravitational-wave observations.
