One of the biggest roles many of us play in life is that of spouse, and the loss of a spouse is considered one of life's most traumatic events. It's very possible to take two to four years to recover, although there's no set timeline for grieving and recovery. Even those who appear to recover quickly may continue to grieve deeply for some time.
Over time, the grief will lessen. There are, however, always times that will be difficult for the surviving spouse--holidays, birthdays, anniversaries, and other special occasions can cause grief to resurface, as can memory cues such as a favorite song, a fragrance, or visiting a place that was special to the two of them.
Again, being a spouse is a major role in our lives, and the loss of a spouse forces us to redefine ourselves and our roles in life. The survivor must find a new purpose and focus, create new goals, and redefine his or her life as a separate human being. This is a difficult and sometimes frightening process, and typically causes the survivor and those around him or her significant pain.
The survivor may have difficulty making decisions or develop irrational fears (e.g., of the dark). Other symptoms you may encounter are forgetfulness, anger, and guilt. Keep in mind that the survivor will work through these feelings, and that he or she desperately needs your support during this difficult time.
"Secondary losses" will usually impact the survivor as well. Each spouse has various roles in the family and household--for example, one may have taken care of the yardwork, been the primary breadwinner, managed the family's finances, or run the social calendar. The loss of the person also creates a hole where this role was. These are skills and roles that must be filled in some other way.