My wife is on antidepressants and has been for a few years has it helped our SL yes because she's allot better off when shes on them. It probably doesn't do anything for her "drive" and this seems to be the focus of your question. I would probably say that her drive in acording to most warnings has a high possibibilty of being dampened by the takeing of antidepressants. Welbutin is supposed to have the least sexual side effects.
Don't think for a moment that there is a pill out there thats just going to change her level of desire. Depression is much more than just a depressed libido. Living with a spouse who is suffereing from depression is no easy task how much caretaking and how much you can actually do is limited. If you want to see where the boundaries between you and others are have a relationship with someone who is depressed. There are times when you have to absolutely step away and let them be and not take on their emotions. I can see that if someone were in a highly "fused" relationship that a partners depression could be devistating.
I guess my question for you is are you concerned about your wife's mental health or getting laid?