Have you outright asked the other woman whether your talking helped lead to her behavior? You all are in the dark, talking to one another when neither of you know what the person with the "problem" thinks/feels.

I would discuss this issue with the group, not let the leader "decide" for you or even you decide for yourself without their being part of it. Group is group; with most groups I've been in there's a rule you're not supposed to have side relationships for this reason, it gets the group all unbalanced.