What were the reasons for the rapprochement between the Soviet Union and Germany?

What were the reasons for the rapprochement between the Soviet Union and Germany? Why was it difficult for the USSR to find mutual understanding with the countries of Antlanta?

The main reason for the rapprochement between the USSR and Nazi Germany was the reluctance of the countries of Western democracies to sign an equal treaty with the Union, under which each country, having been subjected to aggression, receives immediate assistance from the countries participating in the treaty. A striking example of the desire of Western countries to just drag out the time was the arrival in Moscow in August 1939 of the delegations of England and France, who did not have the authority to sign the treaty. Meanwhile, Germany’s aggressive policy gave no reason to doubt that an attack on Poland was a matter of the coming days. And in the event of further delays in negotiations, Germany will simply occupy the entire vast territory of Poland, bringing its borders closer to the most important centers of the Soviet Union. Mutual understanding was difficult to find because the Western countries did not want to fight “for real” and because of the too striking gap between the ideologies of the USSR and the Franco-British coalition, which was later confirmed.