Ok, down to earth straigh forward woman here (lol). Several possibilities:
1) Too tired: With 2 children, cook, clean, feed fam, laundry, housekeeping, nurse, grocery's, nurse, teacher, woman....too tired for intimacy...you get the picture.
2) Health - Starting menopause, which feels like a walking, living hell. Hot flashes, night sweats, mood swings. Many uncomforable changes that are very physical and do affect quality of life.
3) Unfaithful - When a woman does not want to have sex with her partner and does not have the above, infidelity is a possiblity. (I know...i did it, but wasnt married). I just no longer was sexually attracted to him, because I found me another. Sad, but true.
I hope we all have helped and if you have any other questions, you have me, Mami and Teko to be your guiding light (lol)...best of luck...Judy
My first thought would be just what Miami said, the second would be almost impossible to guess with so little information. Have you tried talking to her?
She may need to go to the doctor to check her hormone levels. Sometimes the older we get our bodies go through hormonal changes. It has nothing to do with you I'm sure.