To me the quoted lyrics sound like American Country Western music, so I'm surprised to hear that it's Irish. Country Western music often uses one of the American dialects that has "don't" in place of "doesn't."Thanks all,
it's grateful to receive answer for irish & england people as,it's a song's lyric of The Script ("breakeven"), irish band so I guess you know exactly why do they say like this... I firstly thought it was cos the rhythm of the music... but I wasn't sure... so thanks.
Ah!... the phrase or context is "cos when a heart breaks no it don't break even..."