Enquiring minds want to know!

A famous Mexican song, La Llorona (sung by Joan Baez, Tish Hinojosa, and others) is -- at least in one guitar version -- in A minor. The chorus does something strange: can anyone explain why?

Verse in Am:
Salias del templo un dia, llorona,
cuando al pasar yo te vi;
(repeat)

Chorus:
Hermoso huipil llevabas, llorona,
que te virgen te crei.(repeat)

The song is in 6/8. Easy strum: thumb, strum, strum; thumb, strum, strum.
Chords are:
Verse: Am/Am/Dm/Dm//
Am/Am/E7/E7//
Am/Am/Dm/Dm//
Am/Am/E7/E7//

Straightforward: major substitution of the E for the V7

then Chorus: Am/Am/G/G/F/F/E/E//(repeat).
What kind of a progression is going on here? Some weird Mexican thing, or something normal. Sounds great, but what is officially happening?

yours, Peter T.