The expansion of the universe and the force of gravity are separate phenomena that operate on different scales.
On a cosmological scale, the expansion of the universe is described by the concept of the cosmological constant or dark energy. This expansion refers to the overall stretching of space itself, causing galaxies and other cosmic structures to move away from each other over vast distances. The expansion of the universe is observed through various observations, such as the redshift of light from distant galaxies.
On the other hand, gravity acts on a local scale, influencing the motion and interactions of objects within a given region. Gravity is a fundamental force that attracts massive objects toward each other. While gravity can counteract the expansion of the universe on local scales, it does not directly increase in strength to "keep distances constant" as the universe expands.
The acceleration of the universe's expansion does not lead to a proportional increase in the force of gravity. Instead, it's the relative strengths of dark energy and gravity that determine the long-term behavior of the universe. Currently, the prevailing understanding is that dark energy dominates on cosmological scales, leading to the accelerating expansion of the universe, while gravity dominates on smaller scales, such as within galaxies and our local cosmic neighborhood.
It's important to note that our current understanding of these phenomena is based on the best available scientific theories and observations. However, cosmology and our understanding of the universe continue to be active areas of research, and further discoveries and refinements may refine our understanding in the future.