Since marihuana can meanwhile be legally prescribed, I would want to think of it being just as both enjoyable and harmful as drinking or smoking, which is usually not at all if done in moderation.
I've gone through some weird accidents followed with bouts of tremendous pain, killing cramps and other assorted ailments myself. The pills the doctor could and would prescribe helped a bit, but came with a boatload of new problems and issues that basically just replaced the problems I started out with. Smoking weed moderately did help alleviate both the pain and the cramps - and almost instantly so, and I got to know a wide range of very different people that used weed therapeutically in the process.
I was amazed, to be honest. Still, those folks are a silent minority of weed users who do it because they have a proper reason beyond enjoying the altered state sought by confused, annoyed or anti-social youth. Most of those with medical problems that don't go away, ever, enjoy the healing and soothing effects of the drug in a smoke-free form, so there's no tobacco or open fire involved, just vapor.
There are people who enjoy alcohol, and others who get rather mental and very sick from it. There's an impressively long list of what damage excessive alcohol consumption can do to body and mind.
There are people who enjoy smoking tobacco. I happen to like the non-inhaling varieties to keep my given set of lungs functional, but the smoke could still give me plenty of cancer in the mouth, the throat or any place else. So smoking, in the end, doesn't seem that cool to me, really.
A big problem with weed - beyond the legal implications - is that almost everyone who enjoys its effect is smoking it. While I have met a few people who have behaved rather strangely while under the effect, most people tend to get either a little bit too happy for their own good or they get a bad spell of mañana, which could cost them their relationship, their job, their everything.
So, while I generally don't think asking complete strangers on the web what to do is an excellent idea to begin with, my thoughts on the matter would distill to this: Couples either manage to accept each other as they are and live happily ever after, or they try to change each other, which is always second best to changing oneself. If your education, job or whatever background makes you intolerant not to the drug smuggling problem, the drug dealing problem, but the - suspected - drug consumption problem in your relationship, it's an issue that warrants to decidedly look the other way or discuss it in proper, once and thorougly, not every time envy or fears invade because of lingering issues big and small.