Erectile Dysfunction

My boyfriend and I have been dating for 2 years. We used to have sex quite often (4 or 5 times a week) but now it's MAYBE once a month and he cant keep it up or finish, even from a handjob or blowjob.

He has an alcohol addiction (at least 5 or 6 beers a day, 7 days a week) this the main cause for not being able to keep it up or finish? Or do you think it could be something else?