I don't have much to say other than to relate to what you're experiencing. My husband and I are new to poly (8-9 months?) and I recently began seeing someone after months and months of just talking about it incessantly with husband.
His reaction was similar to your friend's husband's reaction (he loves me and wants me to be happy, and is trying to adjust to my needing to have a relationship with another man). Every day it was a new emotion - very wishy washy. My lover has been understanding, then puzzled, then irritated and frustrated. And then he felt guilty (for "causing our marital strife" - not true). He is now keeping himself at somewhat of an arm's length as my husband and I try to work through my NRE with lover and our new-to-poly adjustments.
All I can say is, it takes a LOT of time and WORK to make these relationships successful. A LOT.
Be patient with him. He deserves it. My husband deserved it and sometimes I'm not very good at being patient. And it's not fair to him. He's trying to accept all of this with the hope that our love and relationship will sustain and remain strong. I imagine this is what that husband feels, and it really is a struggle. I'm sure it's putting him through an emotional ringer.
You might want to just lie low for a bit and give him (them) some space. For us, talking about it every single night was not a great thing. Everyone needs a respite sometimes.