hello robin, welcome to the forum. There are many ways to do poly and it is really individual. For me however and what I suggest to others is that they go at the pace of the one struggling the most. I understand that your wife feels held back so working out the pace is your best bet. Maybe this means she only has a date with this man once a week and spends two dates with you. Maybe it means that the three of you spend time together so that you can get used to his presence in your life. I don't know what would work for you, but negotiating boundaries is huge in poly. That has been my experience anyway.
I suggest that you look at some threads in the sitckies on the foundations of poly, the lessons we have learned and get an idea of how to proceed. You can do a tag search for "foundations" and "lessons" to find some good stuff. There really no need for all or nothing. A balance can be created so that you can catch up and she can feel she has some control. It seems in poly and relationships in general, that they don't survive if one person dictates what happens.
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