To come to be in a position between someone or something and someone or something else, perhaps as a barrier or obstacle between the two. Can be used either literally or figuratively. The teacher got between Mike and Billy to stop them from fighting. I hope you won't let these stupid rumors get between us. This piece is here to make sure the moisture doesn't get between the outer layer and the inner layer.
get between (someone or something and someone or something else)
to position oneself between people and things, in any combination. She got between Dan and his career. The dog got between the archer and the target.