Hi anger is a behaviour. We need to consider if your fiance had anger issues even before the depressive episode.
We also need to see if your fiance is still suffering from depression and anger issues is part of it.
Also depression is treated with psychological therapy which will also help with anger issues.
Next Steps
please consult a Psychiatrist or clinical psychologist
Health Tips
support him. ask him to avoid smoking alcohol and excessive caffeine. physical fitness will help