A) A child's natural disposition towards separation
Even if they have a close and loving relationship with their caretakers, some kids are naturally more anxious about separation. If you're a child, being separated from your primary caregivers can be just as lethal as any other danger. Some kids seem naturally more anxious about this threat.
B) Insecure attachment experiences
The term attachment refers to how secure children feel about the love, affection and responsiveness they receive from caretakers. Children who have disinvolved or erratic caretakers (especially during their early years) often develop an insecure or disorganized attachment style. When love, attention and affection are viewed as less stable and reliable, children will have a harder time managing separations.
C) Stressful transitions
Separation anxiety can be brought on by stressful life events, such as the start of school, experiencing a family move, or enduring instability within the home.
D) Separation anxiety caused by trauma or loss
It's common for children to experience separation anxiety following a trauma or disruptive life event. Such traumas can include divorce, parental abandonment, living through a natural disaster, witnessing domestic conflict or community violence, parental incarceration, or experiencing the loss of a loved one. Any trauma that results in separation from or the death of a loved one is especially likely to result in separation anxiety, since this sudden loss leaves a child fearing that other people in their life might suddenly vanish.
E) Overcontrolling & co-dependent parenting