But recently, she invited herself over to his apartment and stayed there over night over the weekend. He says nothing happened and that he slept on the couch (he even asked me if it was OK before it happened and I trusted him and thought it was a one time thing, so I said ok). But then she stayed over again the next weekend (he did tell me before again), but they didn't mention that it was two nights this time. All of this, I think I might be able to stomach, but then I found out they got high together (he's quit for a while now and he told me he'd never do it again) and then she even convinced him to try poppers. The worse part is that he told me they went to a sex shop together to get the drugs.
For me, I feel like this is overstepping the boundaries of friendship and it makes me really uncomfortable just thinking that they went in there together, regardless of whether they did anything or if they feel any sexual attraction for each other at all. Is it wrong of me to want him to back off from her and not do that again?