It happens, remember ADM Borda? Committed suicide because of some sort of issue with allegedly unearned ribbons.
After 25-plus years of Service, my experience tells me general/flag officers almost exclusively commit suicide to avoid disgrace before some sort of legal trouble which would result in loss of rank/prestige/honor/benefits to survivors....pick one or more. NCOs and enlisted ranks are more prone to suffer from PTSD or other difficulties related to adjusting to life after combat. Logically so since NCOs and enlisted troops are closest to actual combat with a few commissioned types thrown in.
So, IF it was suicide then odds are it was likely related to some impending investigation with a less likely reason, yet probable, mental condition.
Regards.
BTTT