Ah, an important thing that needs to be pointed out: the writers do an appalling terrible job at portraying pain and pain management. There is a very clear distinction between addiction and dependence, and they do an amazingly awful job with it. One of my closest friends experiences chronic pain, and they've been screwing this up since Detox in S1. If "being close to an addict" is your barometer for slack-cutting, well...let's just say these writers tend to make it a rather meaningless one.

Forgot to add: I think Wilson knows what he's doing. He's gone through the same situation with three wives (well, nearly; Julie was perhaps a bit more Genre Savvy than the rest, and cheated on him first) and with House as a best friend, there's no way the pattern wouldn't be pointed out to him, then flaunted, dressed up in bright clothing, and paraded down main street. So even if he somehow didn't manage to figure it out himself (which I find doubtful), he'd still know.