I agree mostly with the above, but you're going to have to be very careful due to his cultural differences. If you get too pushy or ask too many questions, he's going to get angry, and shut down completely and you don't want that. You already know that in his culture, they don't talk about this kind of thing, so asking questions is already over the line! So I'd be very very careful about this.

Like has been said, he's been pretty consistent and you have no evidence that he's contacting her so I think I'd just let it go and figure she's just lonely and is trying to start trouble. She MUST know he's in a relationship, so just chalk her up as a bimbo.

Stop worrying -- he chose YOU. God bless & take care. Hugs, Lee