First of all, welcome.
Secondly, it is great that you seem to be calm and collected, but I miss the personal attitude in your post. How does it feel for you? The situation, the things you are asking about and so on? There is nothing that has to be the norm, that you have to feel. No one can tell you what is ok and what not; only you can say what you want. And I am missing your needs here, kind of.
For some more input from others you should answer the questions you are asking yourself. Is it ok for you that she loves him? Any problems when you imagine your wife being in love with another man? Is it important for you that she may have a child with another man, not with you?
I am 'a poly wife' and live with my husband and boyfriend. We even talked about children, but we are new to it and it seems as a big hurdle to master later on our way to really be in the situation to have children in this kind of relationship. My husband wants to be the first one to have a child with me. But that's what everyone has to find out himself. You say that you ok with it and unsure at the same time. What makes you feel that way?
The important factor is how YOU want your life to be. Not what others think should be ok with you.
Facts: 30, female, bi, v-type relationship with Sward (husband, straight, mono) and Lin (boyfriend, straight, mono), poly-fi and co-primary.