“Why do you suppose that it might enhance the Shalom Bayis to use the traditional Mrs. Husband rather than her own name?”
For the same reason that in some families, the wife uses a hyphenated surname, or the husband is comfortable with the couple being listed separately as Ms. XYZ along with his listing as Mr. ABC on invitations, shul announcements, etc. In some cases, in a second marriage with children, a woman remarrying may want to keep the same surname she went by in a prior marriage or revert to her maiden name or whatever. The point is simply that people come into marriages with very different circumstances and different issues of importance to them and particularly on matters that are not strictly dictated by Halacha, they may be able to find compromises on lesser matters they allow both to come away feeling respected. If the format of the surname is such a big issue to the husband or wife, he/she may decide its an indicator of even bigger conflicts in the future and that maybe they are not well matched.