Loss is a common element. It could be the loss of a loved one, like in the story of Lily who lost her parents. Another common element is isolation. Tom isolated himself from his friends when he was depressed. And also, a sense of hopelessness, like Jack who thought his art dream was over and felt there was no future for him.
One common element is a triggering event. For example, job loss as in Tom's case or lack of support from family like Jack. Then there is often a downward spiral. People start to neglect themselves, stop socializing, and their mental state deteriorates further. Also, self - loathing can be seen. Tom thought he was worthless after losing his job and his wife. These elements often intertwine in a sad depression story.
Well, a sad depression story usually involves some form of emotional pain at the start. This could be due to rejection, like if someone is constantly rejected in relationships or at work. Then, there's a build - up of negative thoughts. These thoughts start to control the person's life. For instance, the bullied girl Lily started to believe all the mean things said about her. And finally, a struggle to break free from the depressive state, which is common as the person has to fight against their own negative mindset and the difficult circumstances.