Fascinating- the suggestion is that the "true love" had deserted to the French.

Many people think of the Napoleonic era as the zenith of British patriotism. Yet a significant number of jolly jack tars who fell into French or American hands - for of course we fought the Americans in the 1812 war - cheerfully enlisted under enemy colours, and were hanged by the British if recaptured.

A young Rifle Brigade officer, Harry Smith, found that one of his grimmest tasks when serving with Wellington's army in the Peninsula was to supervise the execution of British deserters found in the French ranks.
(from this Guardian article from 2005)