This chapter examines transitions that occur over the lifespan of romantic relationships, with a focus on marriages or partnerships with a similar long-term commitment. The chapter evaluates transitions that mark the early years of marriage (getting married and becoming parents), are sparked by unexpected challenges during the child-rearing phase of marriage (discovering infertility, learning a child has autism spectrum disorder, and bereaving the death of a child), and reflect developments later in life (living in an “empty nest,” caring for elderly parents, and coping with a partner’s declining health). The discussion of these transitions considers their potential to both undermine and enhance personal and relational well-being and includes evidence of physiological responses to these transitions where it is available. The conclusion highlights directions for research on relational turbulence, as well as resilience, over the lifespan of marriage.