I'm in a long-distance relationship with Alice, and recently, her sister, Betty has started getting very serious with her boyfriend John (talking about marriage and the like). Alice has met and talked to John before on multiple occasions, but remained a less than average levels of communication, perhaps once a week messages and the like.
Recently, John has been contacting Alice more and more, talking about her visiting him (he lives a few hours by train from her town) and sending her drawings and pictures of the "type" of girls he likes. They both share an interest in yoga and stretching so they send pictures of themselves doing poses which I am largely OK with but I feel that he might be asking for them for more than research purposes. I did talk to Alice about this and she realized it too and started sending less and less pictures or trying to cut back on communications, John does not relent.
The main issue:
John has in fact asked Betty to unfriend all her male friends on FB and even made her block and delete all male contacts (including me) on her phone as he gets really jealous and controls her to an extent. I want to communicate to John that him cutting every male (except family) in Betty's life while simultaneously texting Alice and asking for pictures of her is not only unfair but also makes me feel creeped out.
How would I effectively communicate with John that I would want him to stop but not offend him or Betty (she is very defensive of his behavior, she was, after all the one to pass John Alice's number). A bit at a loss here because I live far away and can't talk to John face to face.
Also, not to say anything but in the past when I talked to Betty (before the blocking) about John's rules, she said it was natural for men from his region to do that. Alice and Betty are from Western Europe.