First, let's be clear that the Church has never held that in religious profession Sisters or nuns merely become engaged to Christ or that there is not a genuine espousal in the original Semitic sense. Keeping that in mind let's temporarily hold onto the crude hypothesis put forward by some CV's that some are "engaged" and others are "married" just to explore the importance of omitting the spousal language, imagery, symbolism and the prayer of consecration as the Church requires for a woman participating in both rites (Perpetual Religious Profession and Consecrated Virginity). As I will argue below, you are correct that persons become espoused when they are consecrated. It is for that reason the Rite of Perpetual profession omits this when the consecration of virgins is to be received as well as the Rite of (Solemn or Perpetual) Profession.
My argument went something like this:
1) if the meaning of the spousal imagery, language, and symbolism in the Rite of Profession is essentially different than in the Rite of Consecration of Virginity, that is, if it means engagement in the first rite and marriage in the second (as one CV's argument would imply), why should anyone omit these things from the first Rite? Quite the contrary: if these elements are the means to becoming engaged in the first Rite and married in the second, and one is moving from engagement to marriage, these things should be retained
2) Similarly, if a Religious "consecrates herself" in the Rite of Profession, but is consecrated by God in the Rite of Consecration of Virgins, and if the two prayers of consecration or solemn blessing are therefore different in meaning and significance, then why shouldn't they be repeated in the two Rites? Omitting them from the first Rite for someone receiving/participating in both Rites only makes sense if their meaning is essentially the same. Otherwise the Church's concern with duplicating these portions of the Rites is unwarranted. There are theological reasons for confirming Religious do not "consecrate themselves" but this underscores those.
3) Espousal only occurs once, and for this reason the Church omits all associated spousal language, imagery, and symbolism from the first Rite (Solemn Profession) ONLY if the nun is going to also participate in the Rite of the consecration of virginity. The dynamic of dedication and consecration which forms a whole is only "completed" in the two Rites together when a nun is ALSO receiving the consecration of virgins.4) Similarly, it is because the language, imagery, and symbolism is part of effecting and marking the same espousal that the Church includes it in the Rite of Solemn profession for those NOT receiving the consecration of virginity. Likewise the prayer of solemn blessing or consecration (also an effective or performative language event) is used in profession for those NOT participating in the Rite of Consecration of virginity because such a consecration is received only once. In other words the act of mediation of God's consecration of the person by the Church symbolized in the prayer, even when the two Rites are separated in time, is only accomplished ONCE for each nun but it MUST be completed in one Rite or the other because the nun does not consecrate herself.
5) What differs (or can differ) is not the basic spousal bond, but the graces, charism and commission attached to the two vocations. My sense is that ordinarily the consecration of virginity makes more explicit the spousal bond but this may not always be so. What emphatically would NOT happen in a monastery of nuns for instance would be some being "engaged" to Christ and others actually "married" to him. In all cases, whether through the consecration of the rite of religious profession or the addition of consecration of virginity the Sisters are espoused to Christ.
I hope this is helpful.
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