OP,
Honestly from my perspective having been in many situations like this... From the girl's point of view, I would rather neither you, nor A, talk about A's feelings toward me. Not you to me, not him to me, not you to him, and vice versa.
If it becomes a problem, where it is interfering with any of the relationships between any party, then it needs to be dealt with accordingly.
If A loves her, then he will want what will make her happiest, and if that's you, prove it to him with how you act around her and how sensitive and respectful you act around him.
You have the benefit of sympathy with A.
Kind Regards,
Hayden
EDIT: I did not see that you closed the thread right before I posted. My apologies.