Is it normal for my wife to lose her drive after taking the depo shot?

My wife was on the depo birth control shot for six months about a year ago. she has returned to the pill. She chose to after gaining wait wich was an expected side effect, However my wife has also lost all drive. She is very depressed she has been told it is due to the shot. Is this true? We were also told it would wear of, Will it? We were both very ual and we are having a very rough time. Is there anything we can do to bring back the Drive? I love her and would never think of cheating or leaving im mostly worried about her becoming dangerously depressed.