My husband is such a gem! Several years back when my kids were much younger and much more demanding and I was homeschooling several children and trying to juggle toddlers at the same time, my husband, seeing how frazzled I was, would occasionally give me private "mommy time," while he took care of the kids. Sometimes I left and went shopping or out to coffee but often I didn't really want to leave, but just to be left alone.
We came up with an alternate plan:. Daddy would tell the kids, "Mommy's going on a date by herself," and they would hug and kiss me goodbye, whereupon I would go out the back door. He would have the kids occupied inside so that they didn't see me sneak around to the side of the house and come into my bedroom through the sliding glass door. Of course I was very quiet, sometimes taking a long hot bath by candlelight or working on some project or just reading a good book. My husband would sneak food into me and the kids were none the wiser. I wouldn't come out of hiding until all were tucked securely in bed.
Not only is it OK for moms to get away from their children occasionally, I think it is imperative, especially if she is feeling stressed and harried. It is better for everyone in the family if Mom has a chance to relax and unwind; times of refreshment for mom help her to be more calm, happy, and able to cope with the pressing duties of motherhood and homeschooling.