We present data from 4 lesbian and 5 gay male same-sex couples who have been together 20 years or more. Couples included those legally married and unmarried, with and without children, and were interviewed within the first year legalized same-sex marriage was enacted in Massachusetts. Using life course theory and case study methodology, we investigate supports and constraints related to relationship longevity and how these factors influence the couples' responses to the option of legal marriage decades into their relationships. Seven out of 9 couples married immediately or soon after legalization. The two who did not marry reaffirmed and maintained their commitment. Results are discussed in light of theory and practice within the context of a period of historic change.