Is a man's oath to his fiancée, "If you enter a certain house, you are forbidden to me if we get married," considered a divorce?

If he intended zihar, then it is effective according to the majority of scholars, and it is forbidden for him to have intercourse with her before expiating for zihar. So, if a man says to a non-mahram woman, "You are to me like the back of my mother if I marry you," the zihar becomes effective according to the Hanafis, Malikis, and Hanbalis. If he then marries her, he becomes a muzahir (one who has committed zihar) and she is not lawful to him until he expiates. However, the Shafi'is hold that zihar suspended upon marriage does not become effective. But if he intended it as an oath or did not intend anything specific, then he is liable for an oath's expiation if he marries her and she enters the designated house.