Since no one can see into the future, no one can guarantee that they'll never drink again. You can shout it from the rooftops and believe it 100%, but that's still no guarantee. I would want to know if someone I was dating had a problem with alcohol in the past. It's only fair that I be the one to choose whether or not to continue the relationship under those circumstances. To keep something so important from me is not only totally unfair, but it allows the other person to make my choices for me. If they cannot be completely honest, then they aren't relationship material, IMO.