He's a man. He just hasn't noticed what you've been eating for the past four years. Though the time passed, he was oblivious to it, because to him, four years is just a little blip in the longer span of your life together. To you, it's been momentuous, and marks a big life change, like the date of a rebirth. For him, it was just different stuff on your plate, and his mind was elsewhere, on other important Man Things.