Regarding your assertion that "chosson & kalla shouldn't see each other during the week before the wedding.":
You may want to read Rabbi Dr. Ari Zivotofsky 's essay on the subject of What’s the Truth about ... a Chatan and Kallah Not Seeing Each Other before the Wedding?.
"This practice has no basis in Talmudic or medieval writings, and the absence of early literature suggests that it is of recent vintage."
It has been suggested that this custom of not seeing each other a week before the wedding is based on superstition and was widespread among AngloSaxons and other medieval peoples.
They had arranged weddings, which were often called off when the couples saw each other before the nuptials"
He brings anecdotes from previous generations when this custom was not all that popular.
(As an aside, in my parents circles the custom was 3 days, not a week.)
As to your question, about dam chimud, he further states:
"Rabbis Kaplan and Forst both suggest that the rationale for the custom relates to the halachah of dam chimud—concern that meeting the chatan may cause the kallah to have a
discharge that could invalidate the shivah nekiyim (seven clean days before going to the mikvah).
However, the logic here is flawed. Chazal (Niddah 66a; YD 192:1-3) require that upon accepting a marriage proposal or setting a wedding date, a woman has to observe seven “clean days,” due to the concern that she may discharge some blood as a result of the excitement. However, this halachah only applies to her initial acceptance of a marriage
proposal. Even if a woman accepts a marriage proposal without ever seeing her intended, upon seeing him, she need not be concerned about dam chimud.
Thus, the link between the halachah of dam chimud and the need to separate the week before the wedding seems weak at best.
Even Rabbi Forst, who cites dam chimud as a basis for the practice, concedes in a footnote: “Nevertheless, the hypothesis that the custom is based upon the chance of dam chimud is difficult to accept.” He concludes by stating: “The purpose of these lines is merely to show that the custom of not meeting one another has no basis in the halachah of dam chimud, not to belittle the custom.”
Ironically, dam chimud might be a reason that they should see each other, because according to the Talmud (Niddah 20b), a woman who pines for her absent husband will experience dam chimud.
My conclusion: Your question is valid - and the custom is widespread but faulty.