Another translation (of a single verse) that I have is:

Why is it anger, O Myfanwy,
That fills your eyes so dark and clear?
Your gentle cheeks, O sweet Myfanwy
Why blush they not when I draw near?
Where is the smile that once most tender
Kindled my love so fond, so true?
Where is the sound of your sweet words,
That drew my heart to follow you?