Please explain sir thomas wyatt's poem "A Revocation"

--Since Faith is dead,
And Truth away
From you is fled?
Should I be led
With doubleness?
Nay! nay! mistress.

I promised you,
And you promised me,
To be as true
As I would be.
But since I see
Your double heart,
Farewell my part!

Thought for to take
'Tis not my mind;
But to forsake
One so unkind;
And as I find
So will I trust.
Farewell, unjust!

Can ye say nay
But that you said
That I alway
Should be obeyed?
And--thus betrayed
Or that I wist!
Farewell, unkis