In spite of Dr. Kubler-Ross's analysis, the grieving process is not always predictable or linear. A person can move between stages in just about any order and can bounce back and forth between two or more for quite awhile. Since Ianto isn't really getting any sort of emotional help with this, we could expect him to remain in the earlier stages of grieving for a much longer period of time than a person getting more in the way of counseling and support might.