Based on this we can answer the Gemara in Kiddushin from the question of the Avnei Miluim. The Gemara in Kiddushin was searching, from a kedushah viewpoint, for a source that kiddushin cannot be performed on a married woman. The Gemara knew that kiddushin would generally not be valid when performed on a married woman because she “belongs” to her husband. But there are cases whereby a woman is married and only has the kedushah aspect, not the kinyan aspect, e.g. a fetus. The Gemara wanted to prove that even in this case, the kiddushin would not be valid because the woman is nonetheless considered to be one of the arayos.