All the individual causes/circumstances will be different, but the most common factors in the Air Force are the same as in civilian life: work/relationship/financial issues leading to a feeling of hopelessness and alcohol is often involved. Air Force life, like the other services, just amplifies the above stressors.
Biggest issue is a high ops tempo coupled with insufficient manning. Ops/Maintenance/Security Forces are all severely undermanned. Experience levels are very low as well. It's burning people out. Despite Big AF's efforts, visiting Mental Health still carries a stigma and asking for help/saying you need a break can still have negative career implications.
Toxic leadership and risk aversion at all levels are also issues the Air Force.
I still think all the efforts put Band-Aids on the Ops Tempo/Personnel Manning Level mismatches. The way to fix the suicide issues is to stop the endless wars in the Middle East or at least adopt a realistic, sustainable ops tempo that actually lets folks rest and recover in garrison between deployments.