The reasons behind a teen's suicide or attempted suicide can be complex. Although suicide is relatively rare among children, the rate of suicides and suicide attempts increases greatly during adolescence. Suicide is the third-leading cause of death for 15- to 24-year-olds. It's also thought that at least 25 attempts are made for every completed teen suicide. Mental Illness as a Cause of Teen Suicide. Situations often drive the emotional causes of suicide. Bullying, cyberbullying, abuse, a detrimental home life, loss of a loved one or even a severe breakup can by contributing causes of teen suicide. Often, many of these ecological factors occur together to reason suicidal feelings and behaviours.