Most likely undiagnosed schizophrenia - like Luke Batty's father. i.e. "There’s speculation the father had planned the boy’s killing and wanted to be killed by police." Types like that kill others because they want the others to go with them - like it was before things changed.
"Lubitz was engaged to be married next year, but had recently broken up with his finance. It is understood that the 28-year-old was struggling to cope after the relationship failed."
