The study aims to describe couples’ changes in sexuality after non-metastatic breast cancer from a longitudinal perspective. Our research question was: how do couples experience the cancer-induced change in sexual frequency and what are the reasons evoked to explain this kind of change over time? Forty heterosexual couples participated in a semi-structured interview three months and two years after surgery. A reflexive thematic analysis was conducted on a specific question about sexuality from a larger interview guide. The results showed that couples follow multiple trajectories regarding sexuality after the onset of oncological treatment. Most couples experienced temporary or more lasting changes, mainly associated with altered body image and pain. Some stopped having sexual activities at the beginning of treatment but resumed sexuality two years later; others were unable to restore sexuality. However, some couples stayed sexually active all along the cancer journey, showing that cessation of any sexual activity is not inevitable. Sexuality represents a significant long-term issue for breast cancer survivors and their partners. Prompt treatment can prevent sexual difficulties from crystallizing, while preserving the individual well-being and the quality of the couple’s relationship. Health professionals should be aware of the need to screen early for sexual changes, while reevaluating the couple’s situation regularly during care.