I agree with everything you wrote except that you seem to be implying this is a male thing, when it is equally common for a woman to drop her friends once she is in a stable relationship and to become dependent on her partner for all social interaction (the suddenly codependent girlfriend is something almost all men experience at some point when dating). Later in life it sometimes manifests as an obsession with ones children at the expense of everything else. Suddenly all conversations are about the kids, etc. The phenomenon definitely applies equally to men and women.