90% of the time its a combination of illegality or one partner not being able to carry out promised/essential tasks (home maintenance/childcare etc).
My late father for most of his life obtained a quantity of benzos by such tactics that would now be classed as illegal diversion but were OK in the 1970s, and by the 80s he had a repeat script for these things. He only very rarely took illegal drugs simply because they were illegal, and breaking the law would bring shame on his family (though he did other things which were sailing close to the wind but never malicious).
He was 1,62m tall (I am 1,65m of height) and yet could match big Irish builders, bikers etc for partying but still somehow manage to be awake and sober enough when he had to do “Dad” duties. My mum disapproved of many of his friends, other than the Irish gipsy woman we got a cat from (who was a friendly cat to the family, but otherwise so wild it caught the neighbours rabbit and had to be rehomed on a farm) which did show the strength of the relationship as she trusted my Dad enough to visit another woman alone (they worked at the same place – the gipsy woman lived on a caravan with a load of cats and all sorts of other animals.). I though it was cool as “Dad is friends with a witch!”
Unfortunately all the drugs as well as cigarettes, booze and exposure to harsh chemicals from work knackered his insides so he only made it as far as 57 – but Mum and Dad stayed married for all their lives. In the last week of Dad’s life he forgave me for all the times I’d got arrested or otherwise in trouble for using illegal drugs, and said he realised the drugs laws were bloody stupid, and said “why is it OK for me to take my pills, but my son gets arrested for his ones?”
