As visual social mediums, Social Networking Sites (SNSs) such as Facebook and Instagram have been examined under the theoretical lenses of social comparison theory and self-discrepancy theory. Guided by self-discrepancy theory and recent work on romantic relationship outcomes and social media usage, this study examined the relationship between the magnitude of actual-ideal self-discrepancies, photo manipulation behaviors on Instagram, Instagram-related relationship conflict, and Instagram-enabled infidelity and dissolution. A total of 264 Instagram users aged 18 to 63 years (M = 21.34, SD = 4.99), predominately female (75%) and Caucasian (60.9%) completed an online survey questionnaire. Analysis of a serial multiple mediator model using bootstrapping methods indicated that the magnitude of participants’ actual-ideal self-discrepancies was sequentially associated with increased Instagram-enabled infidelity and dissolution through increased photo-manipulation behaviors on Instagram and Instagram-related conflict. The theoretical and practical implications of these findings are discussed in detail.