The purpose of this paper is to investigate the forms of romantic love that have beendiversified in modern societies. In modern times, the forms of romantic love separated from traditional institutions and reproduction has become established. However, the present authors were unable to find any previously published research that focused on capturing the various forms of romantic love comprehensively. One of the reasons is the ambiguity of the concept of “romantic relationship”. In this study, the forms of romantic love was measured by two dimensions, one of which is called nonmonogamy-monogamy axis, and another of which is called abandonment-maintenance axis of personal style. The perspective with these two dimensions is called “orientation in romantic relationship”. The former axis represents an aspect of one’s orientation regarding romantic behavior, i.e. whether one strictly pursue aspecific person as a love object or have multiple relationships simultaneously or successively. The latter axis represent an aspect of one’s orientation regarding romantic relationship, i.e., whether one try to maintain one’s personal life style as much as possible or abandon it easily adjusting to one’s love object. These two dimensions were used to classify 4 types of romantic relationship, i.e. 1） nonmonogamy-abandonment type, 2） nonmonogamy-maintenance type, 3）monogamy-abandonment type, and 4） monogamy-maintenance type. In order to measure two dimensions, “orientation in romantic relationship questionnaire （IRRQ）” was invented. IRRQ was constructed with two scales; 7 items of nonmonogamy scale and 9 items of abandonment scale, and administered to 274 subjects, female undergraduates. The non-hierarchical cluster analysis indicated that “orientation in romantic relationship” was categorized into four types; 1） nonmonogamy-abandonment type, 2） nonmonogamy-maintenance type, 3） monogamyabandonment type and 4） monogamy-maintenance type, by the degree of nonmonogamy score and abandonment score. These results suggested that two dimensional model is useful for evaluating each person’s orientation in romantic relationship.