Background:Intimate partner relationships foster individuals’ well-being throughout the lifespan. However, dissatisfying or conflict-laden relationships can have a detrimental impact on well-being and relationship quality. The majority of older adults live together with a spouse/partner, and intimate relationships are one of the most important social contexts in their daily lives.Purpose:Expanding on previous research, we examined the role of previous conflict on experiences of loneliness and affect in the daily lives of older partners from a dyadic perspective. Relationship duration and quality, personality traits (neuroticism and extraversion), conflict frequency during the measurement period, physical health as well as age were considered as moderators.Study Sample and Data Analysis:We used data from an experience sampling study with 151 older heterosexual couples (302 participants; 65+ years old) reporting on their positive and negative affect, loneliness, and previous experience of relationship conflict 6 times a day for 14 days. Data were analyzed using dyadic multilevel models.Results:For both men and women within couples, previous conflict was associated with an increased experience of negative affect and loneliness and a decreased experience of positive affect. Higher neuroticism predicted less positive and more negative affect following conflict for women and more loneliness for men. Higher relationship satisfaction predicted less increase in negative affect after conflict for female partners. Age, relationship duration, physical health, extraversion, and the number of conflict episodes showed no moderating effects.Conclusions:Our results support the notion that relationship conflict deteriorates emotional well-being in old age and renders older adults lonelier even in the context of intimate partner relationships.