I will just throw in that maybe you want to meet him before they go away together for a weekend? I have read sometimes that people in the bf's position are fine with the situation as long as the primary (you) is an unknown, for various reasons, some of them unhealthy - but freak out and decide they can't handle the reality once they see the living breathing other partner exists and is important.
Not suggesting that the boyfriend is hoping your wife will run away with him at all, he sounds like a nice guy, but I have heard of more than one instance of this happening, so that is why in my relationships we tend to meet the others partners pretty early on. Don't know if the boyfriend is poly or not, but if he isn't that would be more reason for me to want to meet him sooner.
Happiness will never come to those who fail to appreciate what they already have.