The Alcohol use issue, low mood, frequent arguments can be related to each and other. He definitely needs treatment either by medicines or by counseling ( psychotherapy ).
Next Steps
The best way to divert him to the treatment is by supporting him. Advising and ordering to the patient may not work sometimes. You contact a Psychiatrist or a Deaddiction specialist to know the strategies we use for treatment readiness.
Health Tips
Never to start any treatment without informing the patient.