Two masses  $m_1$and $m_{2 }(m1<m2)$ are released from rest from a finite distance. They start under their mutual gravitational attraction then

Mutual force of attraction is same on two bodies,
but acceleration $a=mF$

The magnitude of force is constant but directions are opposite.

 $\therefore$   $\mathrm{a}\propto \mathrm{m}$

As ${\mathrm{m}}_1<{\mathrm{m}}_2\Rightarrow {\mathrm{a}}_2<{\mathrm{a}}_1$

Here, Potential energy is getting converted to kinetic energy.

Therefore, no energy loss.