Christ's reprimand of the Ephesian church, "You have left your first love," seems odd being said to a church that appeared so busy doing God's will.
Christ's first letter to the churches focuses on the Ephesians, a people who succeeded in trying the spirits, but in the interim left [their] first love.
The Ephesus church effectively battled various heresies, for which Christ commends it. However, the members lost sight of the reason, having left their first love.
Unity has to come from the inside out, with God raising a leader which His people, having their minds opened by His Spirit, will voluntarily submit to.
As High Priest, Christ is putting His people through the paces, tailoring the trials and experiences needed for sanctification and ultimate glorification.