The  Ephesians Church was where Paul had preached to both the Jews and the Gentiles at the beginning. The relationship between the saints and Paul began when he stopped by Ephesus and preached the gospel during his second missionary journey [Acts 18:19]. 

At that time, although Paul left Ephesus after preaching for only a short while, the work of the gospel was carried on by Priscilla and Aquila,,, who had stayed behind. 

Paul stopped, again, at Ephesus during his third missionary journey and ministered there for about 3 years [Acts 19:17-35]. Paul braved his life for his ministry at the Ephesian Church during these 3 years. It was a ministry that was marked by his tears and prayers [Acts 20:31].

Then at the end of his third missionary journey, on his way back to Jerusalem, he met the elders of the Ephesian Church at Miletus. From there they parted in tears [Acts 20:17, 36-38]. This was the last meeting between Paul and the church at Ephesus recored in the Book of Acts.