Im having this issue as well. P has become infatuated with my girlfriend of about a month now and I am feeling threatened instead of excited for him. I dont know where to turn or how to deal. The best advice I can offer you is continue counselling and being open. Discuss the matter often. Sometimes it feels as though my relationships are almost consumed by deep important conversation on topics like this one, but it really makes things better to have everyone on the same page...