Yeah, it may not be an alcohol issue. A surprising amount of people, I've found, are just plain pushy and rude. There are people who will monitor the food you're eating when you're at a restaurant, or ask persistent personal questions, or ruin a coffee date with political polemics.
Who cares *why*? Maybe they have deep-seated whatevers, maybe they're just asshats. There are certain verbal self-defense thingies you can employ with people like this (like, just say you're not drinking, then change the subject). But if they persist, why hang out with them at all?
Does that sound really negative of me? Seriously, my group of "friends" has shrunk dramatically in the past decade. Sometime I realized I was wasting whole days and evenings with boring, pushy losers and I was like, "Why?"