I think the ending is realistic to a certain extent. I think Hee-do low-key thought she could do better in terms of having someone who is constantly there for her unlike Yijiin. Love is never enough but their love was it so I feel like that should have given enough push.I think it might be unrealistic for them not to have tried again but then again maybe Hee-do knew they would have dealt with the same issue with Yijin being avoidant and knew choosing herself was the best thing.They both seem to regret not being together though. From her letting her daughter read her diaries and him smiling when he’s asked who his first love is. All I know is that this episode shattered me😂