an issue...
All of us have unresolved issues in our lives - these may come in the form of estrangement from our parents, families, loved friends, or in not being able to come to terms with grief, or in not being able to squarely face an unhappy or difficult situation, or in not having the courage to look at ourselves, especially our bad points....
But, one day or the other we have to resolve these or else we will not be at peace with ourselves...
In music sometimes there'd be this 'discordant chord' that popped up, but then, by a series of other notes and chords it would get resolved and flow back into the music - result - beautiful melody, perfect harmony...