From my perspective (and I am an alcoholic) I would say there are 2 components to drinking - one is habit and the other is physical/emotional.
On the habit front, drinking a glass of wine a night could be just the same kind of ritual as sitting down with a cup of tea or a mug of cocoa - just something that you do as a rountine to relax. It takes about 3 weeks to change most habits (and about 9 months for the 'new' habit to become completely ingrained). So for a 3 week period replace the 'need to have' glass of wine with something else equally enjoyable. Then re-introduce wine as part of your 'new' habit - whatever that might be. Even if you are not a problem drinker, that can be surprisingly tough if drinking wine has become an everyday habit, but you will be able to change it within a short period of time.
On the 'problem-drinking' front, alcohol itself has relatively weak physical addictive properties, what people get 'addicted' to is the pleasure hit, which happens (for people who don't drink much) probably within the first mouthful. That is why it feels good, and why it feels relaxing. The human body however adapts quite quickly to drinking alcohol so gradully over a period of time of sustained drinking, it takes more alcohol to cause that good feeling, and the impact is also subdued. So as an alcoholic, I would keep on drinking searching for that elusive 'high'.
If you are having a couple of glasses a night because you 'need' the feeling it gives you, and if you cannot easily change that habit, then maybe what you are drinking could be a problem.
I didn't become an alcoholic overnight. It started as enjoying a drink on special occasions, extended to enjoying relaxing with a shared bottle of wine with dinner every evening, crept up as I discovered that half a bottle never felt like quite enough - just one more glass would be perfect, and kept on creeping up and up. I have spent way too much money, way too much wasted time, drinking, and I've had a few risky incidents along the way. If you're worried about your drinking habit, then this is an easier time to change it than waiting to see whether is becomes something else.
And I think it is well acknowledged that the 'safe drinking guidelines' are pretty arbitrary, but there is an impact on your body from having to deal every day with a toxin, and bloody hell, it does feel great to wake up without even a trace of a hnagover