Quincy, M.E. - Season 4 Episode 19 Promises to Keep

Quincy and Sam have to stay late, going over work that was completed by a Medical Examiner who, it turned out, wasn't qualified for the job. This makes Quincy miss yet another date with Lynne, his current girlfriend. When they do get together she proposes to him. He turns her down because he remembers how he treated Helen, his first wife. He was always working and never spending enough time with her. Later he feels guilty and decides to go and see Lynne and propose to her himself.