As an Irish singer my favourites would be Tommy Makem's Gentle Annie written for his wife Annie, no pain or sorry just a lovely poetic love letter to his wife
The Rose of Tralee, because of the great true love story behind the song
And Raglan road by Frank Kavanagh, because I believe it's not about a woman at all, but an Irish fable to the country he loved but didn't love him enough in return

Apart from Irish songs, Ewan McColl's The First Time is beautiful and again a true love story behind it