I've certainly found the following three books very useful on Germany at the end of the Cold War and into the immediate post-Cold War period. Mary Elise Sarotte, 1989: The Struggle to Create Post-Cold War Europe (Princeton: Princeton University Press, 2009) and The Collapse: The Accidental Opening of the Berlin Wall (New York: Basic Books, 2014). Kristina Spohr, Post Wall, Post Square: Rebuilding the World after 1989 (London: HarperCollins, 2019)

On Cold War era Germany, I very much enjoyed Pertti Ahonen, Death at the Berlin Wall (Oxford: Oxford University Press, 2011), which is a really fantastic social and political history of killings at the Berlin Wall, from its construction to its collapse. Anna Funder's Stasiland is also well worth reading for insights into life in East Germany.

However, I come at this from the perspective of a Cold War historian, rather than a specialist in German history. I'm sure those with specialist knowledge will be able to offer much more substantive suggestions.

Hope this helps though.

Malcolm