She sees it as quite an unattractive thing and her head is full with all the ignorant, uneducated opinions about drugs fed to people at school.

So you're downplaying her feelings and ignoring how she feels, while indirectly calling her ignorant. Off to a great start buddy.

At the end of the day I consider this to be a very serious relationship...

And you're willing to throw it away in order to get stoned. Interesting priority.

maybe an angle I can take with her to encourage her to accept it or how to talk to her about it.

So you don't really respect her opinion, and you want us to help you change her mind, as if she's not entitled to her own preferences.

You want to smoke weed and do drugs more than you actually care for her, this is a pretty clear cut case of her being better off with someone else. Instead of respecting her preferences you just want information on how to change her mind, which is really fucked up.

She especially doesn't understand how it enhances social experiences...

So what? What you don't understand is that there are tons of people in this world who don't need to get stoned to have a good time, who see drug use as a joke for people who are too boring to have a good time on their own. Don't put your bullshit ideas onto her. She has every right to say she doesn't want to be around it.

You're allowed to bring things up, but keep in mind that whining, complaining and bringing the same bullshit up time and again is obnoxious and unattractive. You gave your word, either deal with it, drop it, or let her move on. This isn't like trying to get over an affair or dealing with personal issues, this is you wanting to get stoned.