The last verse may be in reference to the fact that soldiers could take their wife to the front during the Napolionic Wars. See the section on "Daily Life" in the following link en.wikipedia.org/wiki/British_Army_during_the_Napoleonic_Wars.

Potentially the protagonists "true love" could have married an Irish soldier in the Royal Irish Regiment. The protagonist is waiting for the war to be over. Then the lassie without the land and her husband can come home and he will have a chance to see her again.