This against thee, that (κατα σου οτ). For the phrase "have against" see Matthew 5:23. The οτ clause is the object of εχω.

Thou didst leave (αφηκες). First aorist active (kappa aorist, but with -ες instead of -ας) of αφιημ, a definite and sad departure.

Thy first love (την αγαπην σου την πρωτην). "Thy love the first." This early love, proof of the new life in Christ (1. John 3:13), had cooled off in spite of their doctrinal purity. They had remained orthodox, but had become unloving partly because of the controversies with the Nicolaitans.