This study looked at low self-esteem, happiness, age and jealousy in romantic relationships, to see if these variables are factors of jealousy in relationships. There was 162 participants used altogether, 80 males and 82 females, all of whom were college students in Dublin. Their age ranged from 18-51 with the average age being 24.The questionnaire booklet consisted of three questionnaires Subjective Happiness scale (Lyubomirsky, 1994), Rosenberg Self - Esteem Scale (Rosenberg, 1965) and Pines and Aronson's (1983) 8-item jealousy scale. Participants were also asked for their age and gender. In this study the predictor variables (PV) include self –esteem, happiness and age and the criterion variable (CV) is jealousy. The level of significance for this study carried out is 0.05. Descriptive and inferential statistics were used to analyse the data collected. Correlational analysis carried out indicated for males and females that the lower their self-esteem the higher their levels of jealousy is in romantic relationships. This analysis showed the same result for age and jealousy amongst male and female participants, the older the participant gets their levels of jealousy decrease. For the third hypothesis carried out, correlational analysis indicated a significant correlation between happiness and jealousy for men, their levels of jealousy are higher when they are unhappy, and for women the analysis was not significant between happiness and jealousy with the correlation being 0.6.