A risk present in medically informed psychosocial interventions for dementia, including musical interventions, is the potential to overly prioritise the reduction of cognitive decline, which can inadvertently emphasise deterioration and loss of skills and capacities. This focus can lead to disempowering people living with dementia rather than supporting and building on the skills that remain. In this paper, we present approaches linked with a more positive outlook on dementia, examining the strengths that continue in people living with dementia, as evidenced by how they engage in musical activities. We pay specific attention to how people living with dementia use embodied and relational ways of being and interacting with others, as well as the benefits that musical engagement can provide to selfhood, couplehood and agency in a context of change and adaptation due to the development of the condition. We propose a shift in perspective that takes advantage of music's affordances for embodied communication and connection, recognising people living with dementia as active agents with strengths in habituated ways of acting. With this shift we examine how couples can scaffold each other's abilities to reach towards a balanced sense of reciprocity. To further support this balanced reciprocity through embodied and relational aspects of musical participation, we make a proposal for the design of assistive music technologies that will support notions of we-perspective, joint agency and joint action, with each of these providing wellbeing benefits for people living with dementia and their carers. Drawing on the potential effects that embodiment and relationality have on agency, selfhood and couplehood in musical engagement, we present a case for reassessing the goals and design of musical activities and the technologies to support them.