Question

Why the force of gravity exist between the two astronaut in space

Answer 1

when any two bodies in the universe attract each other with a force that is opposite to the product of their body masses and inversely proportional to the square of the distance between them.

Answer 2

Force of gravity exists wherever you go in the observable universe or might be in the non observable Universe obviously.. The two body of the astronaut has to obey the law of gravitation .. After all they are same .. Their existence is same.. Just you try to stretch rubber bands and it tries to align itself as it was.. Hence they will attract themselves.. Just like earth and sun or any other body in the space