Does this song use chromatic mediant in G major? and what other music theory concepts this song's verse utilize

Question

I'm currently learning basic music theory and along the way I review old songs on my playlist then analyze what key, chord progression and somehow discover the composer's way of creating music.

The specific song "214 by Rivermaya" is clearly written on G major with chord progression of I, vi, ii... in its intro.

What confuses me is the use of E and A major chords in the verse. I just recently explored the concept of "chromatic mediant". Based on its concept, E is the parallel key of G major's sub-median note (E minor). But the A major chord doesn't look like a chromatic mediant since it belongs to supertonic of both G major and G minor scale. What could be the explanation that describes the structure of the verse? Should I also look in the concept of modes or other music theory concepts to easily understand how songs are composed? Thanks!

Answer 1

Seems to me tha verse has actually gone into key E. There are A and Am, both of which are commonplace in key E, and using Bm instead of E7 is a not unusual way to get to IV, A. The Bm has B, D, F♯, so sounds somewhat like E9.

On the 2nd question - modes will and do appear in some songs, although nowhere near as common as the 'main' modes of Ionian and Aeolian, but being aware of where 'home' is - the tonic - will be the best clue as to whether a song's in a different mode.