drugs in the proper sense - 'hard' use (daily or at least habit forming) and 'hard' (i.e. opiates, amphetamines, benzos etc) drugs are never sustainable. we've all heard or lived the stories of monster tolerances, and they just keep going up and up. there is no happy ending to any of those stories.
drugs take time and effort and money. dealers are seldom reliable. relationships are the same in these aspects. in a lot of ways you can draw parallels between drug use and love, as people have said - love is an addiction in almost every way possible. dependence, withdrawal, unreliability, habit forming, all the joys combined with the pains. its another thing in life we sacrifice so much for, and not always get it back in return. at other times we can get a lot from a little sacrifice.
in writing this post i drew a lot of commonalities with love and drugs which i then had to edit out because i realised in a lot of ways it could just equally be applied to 'love' depending on your definition of love. maybe the drug high that a lot of us chase is the 'honeymoon period' feeling some of us chase when it comes to love.
i thought about how love plateaus and thats why its sustainable, unlike an addiction which continues to grow no matter what. i thought then, is love that plateaus, really still the type of love we're considering? or is that just a friendship/companionship which happens to also include sex?
i thought, how many of our long term relationships no longer compare to the first love, the first chase?
perhaps the thing which makes love seem more sustainable is that it usually depends on another person, and is less controllable in life. equally drugs require the same sort of dependence on another person - your dealer or doctor who is also subjective at times and can refuse to sell or script.
sorry for the rant.