Well for me, it's the behavior that goes with the addiction. The lying (before, during and after the act of drinking), the emotional highs and lows, the emotional dependency (on me), the guilt, selfishness etc.
And even in the times when he was sober, we still didn't get along all that great due to no trust at all for him due to his drinking - always waiting for the other shoe to drop. So yes, in a way it was the drinking. My x started drinking at 12 years old. He is one month shy of 40 (God willing) so his emotional level is really far behind I suspect. Like someone else here said - any discomfort - even normal relationship things like needing time apart - disagreements - was an excuse to drink.