Background: Pregnancy loss affects 1 in 4 women and is linked with poorer overall health and relationship outcomes. Despite sexual well-being's importance to health, how sexual well-being changes across time after a pregnancy loss and what might predict such changes, like perinatal grief, have never been examined, leaving practitioners and couples without knowledge of what to expect. Aim: We aimed to examine (1) how sexual satisfaction, sexual desire, sexual distress, and perinatal grief change from 10 to 25 weeks postloss for both couple members; and (2) if perinatal grief levels at 10 weeks postloss predict sexual well-being trajectories. Methods: Women and gender-diverse individuals who were pregnant when a pregnancy loss occurred (within the last 4 months) and men, women, and gender-diverse partners who were not pregnant (N = 132 couples) independently completed 4 monthly assessments of sexual well-being and perinatal grief. Outcomes: Outcomes included sexual satisfaction (Global Measure of Sexual Satisfaction), sexual desire (Sexual Desire Inventory), sexual distress (Sexual Distress Scale–Short Form), perinatal grief (Perinatal Grief Scale). Results: Dyadic growth curve modeling indicated that, from 10 to 25 weeks postloss, both couple members' sexual satisfaction increased, and their sexual desire remained stable; sexual distress decreased for partners but remained stable for individuals who were pregnant; and both couple members' perinatal grief decreased. Perinatal grief levels at 10 weeks postloss did not predict sexual well-being trajectories over time. Clinical Implications: Given sexual well-being's dynamic nature, clinicians should regularly discuss sexuality with both couple members after pregnancy loss. During such discussions, clinicians could reassure couples about their sexual relationship's recovery by sharing that, on average, sexual satisfaction, sexual desire, and sexual distress tend to improve or stay the same (rather than worsen) from 10 to 25 weeks postloss. They can also share that perinatal grief tends to decrease during this time and is unrelated to trajectories of sexual satisfaction, sexual desire, and sexual distress. Strengths and limitations: This is the first study, to our knowledge, to examine how sexual well-being changes across time after a pregnancy loss and perinatal grief's role in such changes. The results may not generalize broadly, as most couples were in mixed-gender/sex relationships, identified as White, and were relatively affluent. Conclusion: From 10 to 25 weeks postloss, both couple members tend to experience improvements in their overall sexual well-being and declines in their perinatal grief. Early perinatal grief levels and subsequent sexual well-being trajectories are seemingly unrelated. [ABSTRACT FROM AUTHOR]