It is known that the female hormone levels fluctuate during the menstrual cycle, which on average lasts about 29 days. The menstrual cycle is divided into three phases: menstrual, follicular and luteal phase. During the follicular phase there is an ovulation, the period when the woman is fertile and ready for potentially conception. The estrogen level is highest a few days before or on the day of ovulation. The progesterone level is highest during the luteal phase of the cycle, the phase when the woman is not fertile. This phase usually occurs 7 ± 2 days before the next menstruation begins and the new cycle starts. Menstrual cycles in women also accompany certain psychological changes and changes in behavior. Such changes occur due to fluctuations in the concentration of sex hormones. Changes in the sex hormone concentration can thus affect the women's romantic relationship, or the various aspects of the quality of the relationship. Romantic relationships are an important aspect of every man's life. One of the observed changes associated with changes in hormone concentrations is the change in female jealousy during the phase of the menstrual cycle.The aim of this study is to examine the changes in the relationship satisfaction and jealousy at different stages of the menstrual cycle, the ovulation stage when the woman is fertile and luteal when the woman is not fertile. This study included 29 students from the University in the Republic of Croatia who are currently in a romantic relationship. Relationship Assesment Scale and hypothetical scenarios of emotional and sexual jealousy with the estimation scale, participants filled out twice during the ovulation and during the luteal phase of the menstrual cycle. Using variance analysis with repeated measurements and t-test for dependent samples, no statistically significant difference in the relationship satisfaction between the two stages of the menstrual cycle was found. Also, there was no difference in estimates of emotional jealousy with regard to the fertile and infertile phase of the cycle, as well as in the estimates of sexual jealousy.