During a marital separation, prior to divorce, if the wife uses the dental benefits of the husband that are provided to him and his family for her use and his stepchildren, is the wife obligated to repay the amount she benefited even though there is no loss to the husband due to her benefit or her children?
Under the circumstances it appears that she won’t have to pay.
This seems to be a case of zeh neheneh ve-zeh lo chaser: The wife has benefited and the husband has not incurred any loss. Because there is no loss involved, it follows that there is no obligation to pay for the benefit.
In addition, she is still formally part of the family, so that it appears that the benefits are really for her use, too, until the divorce is official.