Major Depressive Disorder

Very recently Bob has been diagnosed with Major Depressive Disorder (btw :)!26!:), that's why he gets depressed a lot.) Poverty is often associated with major depressive disorder, so that's most likely how he developed it. Up to 60% of the people who commit suicide have a depressive disorder or another mood disorder, so evidently Lucy had it too. (major depressive disorder also is associated with stress and vulnerability, more proof that Lucy had it.)

Kudos to Wikipedia!