It is legal for a wife to sleep with other mean at any time--being married does not give a husband ownership or control over his wife. (And the same is true in reverse, of course.) The fact that she is having sex outside of marriage, even during the divorce process, is, however, a factor that may come into play during the divorce and can affect the terms of the divorce. So, yes, she can sleep with other men; but it may affect what she receives in the divorce.