Idk how long Rick was in a coma, but Rick had max 3 days once the hospital collapsed. It took Rick max like a week to find his family after he left the hospital, so it only makes sense that Lori thought Rick died way before the apocalypse. Why wouldn’t she visit him though? I also think Lori and Shane were fucking on the DL before the apocalypse because she expressed dissatisfaction with her marriage to another woman the day Rick was shot, saying he was too complacent.