Working in Toronto I found the same. Worse still (and in typical Canadian fashion), people would act as if they wanted to be more than work friends, but outside-work events would never work out for some reason. Moving to the Netherlands fixed the problem for me, so I think there are strong cultural forced at play. I've found building friendships (and knowing who is actually not interested in friendship) much easier, in and out of work. Also, in one year my professional network is far better than what I had in Canada after six years.