I think again, that regardless of what the substance used/abused is, it is up to you as the significant other/family/friend to determine for yourself what is acceptable to you.
There are things I read here from other posters that make me want to scream, "RUN! RUN FOR YOUR LIFE! HEAD FOR THE HILLS! ARE YOU OUT OF YOUR COTTONEFFING MIND WHY ARE YOU NOT RUNNIGN!?!?!?" -- but the thing is, whether it's alcohol or pot or heroin or meth, I won't change your mind one bit by screaming at you. I can tell you how I would react and how I view the situation, but you have to determine what your level of acceptance is.
We've all, as family of alcoholics, accepted things we never in a million years would have thought we would. And so maybe that's why some of us are not very judgmental about how others react. And then again, some of us have seen relationships and brains ravaged by pot abuse -- and we will again have another outlook.