Rush Limbaugh used opiates for 10 years and nobody noticed. I never lost my business or homes while using, it was detox that made me lose it all. As long as an opiate addict has a steady supply, many of them can function just fine. I would not assume pot means a heroin relapse and could be the cause of his mood changes. You can buy a drug test and a pharmacy or Walmart even. You have to catch heroin within a few days of using, but pot takes a couple weeks to get out if the system. He was sneaking the cannabis, so that is a red flag to me, what else is he hiding? Has he denied any other drug use?
This is a really tough position to be in. I can only share my story with you since it is somewhat similar and may help. When I got married back in 1992, I was sober for 5 years. I married a man who got sober to be with me. That was mistake number one. H e started using our first year of marriage and I stayed. Mistake number 2 . Flash forward 13years, I was depressed and then found out he was doing cocaine. I was like a horse led to water but I chose to drink of the cocaine. The weekend person always pulls the stronger one down in my opinion. I was no longer sober and partied with my husband regularly. I lost EVERYTHING, my kids, my car, my home, my family, myself, my mind and my marriage.
Needless to say, I divorced this man and I am now 6 years sober. HIM, daily pot smoker and still a garbage head. He has a good job and stellar credit. Also, a great liar.
So, I don`t have an answer just a story..................
Today I am still working on my credit and I am a good person. I assume that there are addicts who function and lose nothing. I really don`t understand it myself.