My son is doing the same for the past month, he does not love daddy anymore, he wants to cuddle only with mommy, mommy must do this or that, mommy is his best friend or his hero (?), Daddy is just somebody in our household who does not deserve his attention. I feel so sorry for my hubby because he sometimes suffers, he loves so much our son and he's longing for his attention, and what I do is try to have my son involved in all kind of activities with his daddy, but to be honest, I never thought it could be a phase, as somebody pointed out, before the new sibling is coming into the world. I mean, it makes perfect sense to me, he may be unsure of what it's going to be when the new sibling will be home.