on your side persuasion...
i have been through what you are going through, its not easy. it feels like things are falling apart, and heartbreak, like a partner is being pulled away.
just a devils advocate kind of persuasion....
nre is powerful, and typically its not intentional. even if you ask her to examine her behavior, she will likely not realize how those actions lead by her heart, could affect you like that. because only she knows the depth of her feelings for you.
voice of reason persuasion.
after being through this a few times. sometimes us partners need a boost, in our understanding of just how we are felt about. as time goes on, as i have recently discovered, physical attraction decreases, while love continues to grow. chemistry can also give nre a kick in the butt. it can also have an nre like effect on long term relationships, however the chemistry does not always work both ways. so while i am in almost constant nre after 18 years, my ms. is not. she is still attracted to me, just not as powerfully as i am to her. however the important part is the love that we share, that grows every day, that binds us together with a closeness that cant really be described.
i have found in the past, coping with this kind of feeling is lessened when i am in a relationship as well. because the tug of a new relationship, helps counter the pull of a partners new relationship.
try not to assign blame when talking, this has its own pit falls. when you talk, reach for understanding, and try to understand the feelings she is having both for you, or the new interest. once you understand better, it may help you communicate your feelings better and communicate them in a way that helps you both grow through this.
its not just a newbie thing, and i hope everything goes well.