Final answer:
Passionate feelings between two people who don't know each other well can be described as Infatuation, which involves passion without intimacy or commitment. This matches with Sternberg's definition of romantic love which includes passion and intimacy but not commitment.
Step-by-step explanation:
Passionate feelings between two people who don't know each other well is most accurately described as Infatuation. According to Robert Sternberg's triangular theory of love, romantic love is defined by having passion and intimacy, but no commitment. In the context of the choices provided, 'Love at first sight' might be considered synonymous with infatuation, as it implies an immediate passion without deep understanding or commitment. An arranged marriage and mutual understanding do not necessarily involve passionate feelings, especially between individuals who are not well-acquainted.
Infatuation can be characterized by an intense but short-lived passion for someone else, where commitment and a deeper emotional connection, or intimacy, have not yet developed. It is a common experience at various life stages and can lead to a more mature, enduring relationship as the other components of love - intimacy and commitment - begin to develop over time. However, infatuation alone does not fulfill Sternberg's definition of consummate love, which requires all three components: intimacy, passion, and commitment.