In regard to maturity in general, one of my psychology professors once mentioned in one of his lectures that one sign of maturity is when a person is willing to join the labor force or in other words - have a great desire to work! As far as love and relationship is concerned however, there are quite a few facets of an individual's life that you can examine to determine whether or not that person is mature or at least showing some signs of maturity. For example, when a person is willing to be committed to a relationship, that's usually one huge sign of maturity. In some sense, this is somewhat parallel to the theory of civilization. Based on this theory, civilization began when men began to give up their nomadic lifestyles ( constantly moving from place to place) for a more settled one ( From Hunter - gatherers to settled farmers), for the sake of their families and themselves. This to me, is one big sign of maturity! Likewise, a man or woman who is willing to settle down and try to cultivate a future with a person in my opinion, is one big sign of maturity!