I think this harmonizing your relationships idea makes more sense as simply- the things we don't like in others are projections of our own judgements, (not necessarily projections of our own qualities)
And to know that you can change your judgements if you want.
Harmony in relationships, like music, works when two people are alike, in values and qualities, and also when they are complementary. Either matching or complementing tones.
Disharmony or dissonance occurs when people are different, and those values don't match up, neither alike nor complementary.
Therefore, in relationships, the qualities we don't like in other people are usually because they don't match or complement ours.
Sometimes this signals elements that we need to work on ourselves (eg becoming less judgemental and more accepting) but I think that those elements are rarely the things that we are judging in others, imo.