I would like to submit that maturity matters most of all in romance, and by maturity I mean selflessness. An immature SJ may have more problems in a relationship than someone of a stereotypically flighty or critical temperament who is highly motivated to remain committed. I think that romantic relationships are a crucible in which temperament is refined...there is a feeling that we "shouldn't have to change," but we all start life in a pretty selfish state, regardless of temperament.