In fact some studies in men have shown they have increased libido on Naltrexone.
There is of course underlying issues and if it's a problem for her, note: I said her... not you

then she should seek counseling. Alcohol as we all know and for many of us who started drinking as teen agers is one of the drugs that reduces your inhibitions and turns you into a super star! Sometimes people use it to loosen up to be able to do things they might otherwise be inhibited or shy in doing. I know that was the case for me. If that is the case for her then it simply needs to be addressed.
The fact of the matter is this, alcoholism is a very selfish sickness and it is a personal journey. TSM is the reverse of that and is equally as selfish and personal. Right now your wife is doing what she needs to do for Number One, herself, and at all other cost she is saving her own life. Once that begins to take hold then you will really start seeing the benefits as it seems you already have.
I wish the best of luck to her.