Good to hear things seem to be going well between you two.
As for your friends, chances are you really can't. I think it's great that you trust her to have her own life outside of the relationship (from what you say.)
Were it I, I'd probably say something like, "You guys just wish you could find a girl you could trust." or something like that. I'm not known for my kindness, though, so maybe that isn't the best idea.
