The clinical presentation of depression often develops from psychological pressures.
My mother threatened suicide often when I was a teenager. She would go out in the middle of the night and park at the edge of a quarry or head for the turnpike, intending to do a u-turn and drive against traffic. For one reason or another, she always gave up and returned home at dawn, in time to go to work. She said that the reason was that she had too many responsibilities to end her life.
There is situational depression and there is clinical depression. All of us at one time or another in life suffer the former. Others, such as myself, at one time or another suffer or have suffered from the latter.