I'm having a bit of a dilemma, so thought some outside perspectives might be helpful.
I've got a friend, who I've known for a while, but generally keep a bit at arms length for various reasons - most of all because he seems to have very narcissistic tendencies. He's been seeing his current girlfriend for almost a year and, from what I can tell, it's a very up and down relationship. The main issue is that he's constantly slagging her off - bitchy about her past relationships, friends, the way she acts when she's had a drink, doesn't seem to trust her (he goes through her phone regularly, although I don't think she knows) and is incredibly dismissive of her opinions or when she defends herself. The thing is, he says all this to me, but doesn't say it in that way to her. It's more that he'll say something like "it just hurts that you had these past experiences, but I don't want you to feel guilty", but then calls her a slag to me. I call him out on it constantly, particularly if I see him face to face on occasion, but he says it's all on her. I've nearly ended our friendship over it, but I feel like I kind of need to fight her corner a bit. He's been no angel himself, so it's very hypocritical - and he's not told her anything about his history as "she doesn't need to know".
Anyway, he's told me he's planning to propose, and that she should feel honoured that he's giving her this opportunity!!! I suspect it'll be this huge romantic gesture, with no mention of that. And I suspect he's probably ground her down so much that she'll genuinely feel grateful! Otherwise, I can't see how she's stayed in the relationship!
I guess my IABU is, would it be awful of me to try to contact her (we've never met - we live at opposite ends of the country) to warn her, or should I just stay out of it - it's none of my business.