The USSR in 1952, via memo known as "the Stalin Note", proposed a reunification for Germany along with disengagement of superpowers from the region.
What were the reasons for the Western allied powers (UK, USA and France) rejecting this proposal?
Two: the implied inclusion of some representation of the GDR authorities in an "all-German government", and neutralisation. After 1949 the western powers were set on recognition of the FRG as Germany's legitimate government, resisting the claims of the eastern regime that they viewed as unelected and subject to Soviet control. By March 1952 Bonn's inclusion in the proposed (western) European Defence Community was also on the cards, the alliance's subsequent demise at the hands of a parliamentary coalition of French Communists, Gaullists and others not yet foreseen.
Ultimately the western powers preferred an allied three-quarters of a Germany to a neutral Germany that they might regard as being of questionable democratic legitimacy. Their response suggests that they rejected the proposal principally for the very reason it commended itself to Moscow, in that it would have drawn western forces back from the Elbe to the Rhine (while consigning Soviet ones to the Oder). To the Nato powers that was a net loss, as indeed it would have been.