Is expiation obligatory for every handshake with a non-mahram if it occurred in an embarrassing situation?

If a wife breaks her oath by shaking hands with a non-mahram, she is obligated to offer an expiation for breaking an oath (kaffarat yamin), and her oath is then dissolved. Therefore, she is not required to offer another expiation for shaking hands again, because the wording of her oath does not necessitate repetition. It is not permissible for the husband to permit his wife to shake hands with a non-mahram, even if he is a relative to her, and it is not permissible for her to do so out of shyness towards people.