Fare thee well sweet Mary MaGornan,
It grieves me to leave thee dear bride of my soul,
Fare thee well sweet Mary MaGornan,
It grieves me to leave thee dear bride of my soul.

The story:

Mavoureen sounds similar to MaGornan I suppose. Not
much of a story really, I did keep searching on-line
to see who this Mary MaGornan was but unsurprisingly
enough only found people that have/had names of Mary
Magnan.