One of the important mantras you often hear when discussing poly-style relationships is that you have to go at a speed at which everyone involved is comfortable.
This means two things - the person who isn't comfortable with the speed that things are progressing needs to speak up, and the others need to listen and respect and not make the other feel bad because they said anything.
This can be frustrating, but as long as everyone knows that each of the people are acting in good faith towards making it work, it can be done.
Please check out The Birdcage - an open, friendly Polyamory forum for all parts of New York State
"Listen, or your tongue will make you deaf." - Native American Proverb