Thanks, for the advice I guess when we opened up our relationship we said neither of us wanted a second relationship so I was unsettled when this developed. Also while we were both eager to share our experiences with the other people we have been with I am feeling more left out in this new relationship.
Because I'm friends with this girl we agreed that she would be uncomfortable with me knowing details of their sex life, and she has a right to privacy. Whereas before sex with other partners was something me and my boyfriend liked to share and bond over. I know communication is important in this situation, and while we are good at talking about our own relationship, I guess I'm unsure about how much I can know about his second relationship, I'm trying to balance their privacy with wanting him to share more with me.
I will discuss this with him and like you suggest talk about our new boundaries. Thanks also for the link.