In: Psychology
There may not be a definite answer to state which of them either boys or girls are true to their relationships in traditional culture. I would like to state the example of Indian culture. Mythology states that Man is of a caprese nature, he is a river, or a wild animal and its a womans job to tame the animal. Therefore a woman has a job to look at her best, be sexually giving and cater to all the man's needs, then only a man will be true and stay committed to her. So a man's honesty and commitment towards a relationship depends on the woman.
Any feminist would disregard this and say that it is not solely a woman's job to sustain the relation. They would state that its a man's job to keep the woman happy by giving her what she damands in terms of objects.
However, according to me, stayin honest in a relationship, even during adolescents depends upon what is an individuals understanding of a romantic relationship. And also what kind of role model the adolescent may have had in deceloping years. It is not on the type of gender to decide wether who stays true or who cheats, but rather personality factors, upbringing, emotional give and take in a relation and previous experiences which are the detrimental factors in identifying the sustainability of a adolescent relationship.