The Gemorah (Kiddushin 2b) tells us that the phrase "harei at m'kudeshet li" that we use under the chuppah is not a biblical expression at all, rather it is a rabbinical formulation. However, the commentaries on the Gemorah (Gilyonei ha'Shas by Rav Yosef Engel, Kiddushin 41a) point out that the concept behind the expression is in fact biblical. Specifically, we assume that when a Jewish couple gets married, an element of keddusha is introduced into their lives. The Gemorah (Sotah 17a) points out that in the Hebrew language the word "ish" has a letter "yud" and the word "isha" has a letter "hay", and combined these two letters spell out the name of Hashem (yud - hay.) The Gemorah also tells us that when a couple has shalom bayis, "shechinah sh'ruyah bei'neiyem" - there will be an element of keddusha in their lives.
When the Torah tells us the laws of the sotah in Parshas Nosho, the verb that is chosen and repeated three times in the posuk is "v'nitme'ah." Why should that verb have been chosen to connote ruining a marriage? The Avnei Nezer explains the choice of this verb by quoting a section from the Kuzari in which the king of the Kuzarim asked the rabbi, "if you Orthodox Jews follow everything that it says in the Torah, why don't you go to mikva every time you come in contact with tumah as prescribed in the Torah?" The rabbi responded that the laws of tumah are only relevant when you are dealing with keddusha. For example, the Beis Hamikdash has keddusha and one who is tomei may not enter; korbonos, maaser sheini, and terumah have keddusha and one who is tomei may not eat them. But we live so far away from the Beis Hamikdash - we have no terumah and no korbonos, and nothing of keddusha to speak of, and therefore we don't have to go to mikvah. Tumah is only an issue when it is in contradiction to keddusha; if one is nowhere near aspects of keddusha, then the tumah is irrelevant.
Based on that comment of the Kuzari, the Avnei Nezer (Even Hoezer, 240,5) explains that the Torah seems to be assuming that every Jewish marriage contains an element of keddusha. When dealing with a sotah, i.e. a marriage that was ruined, the Chumash can use the word "v'nit'meah" exactly for the reason of the Kuzari, i.e. that tumah is a contradiction to keddusha. This interpretation of the posuk is not merely agadata - it is a halachic realty that the Avnei Nezer uses to explain some halachos in that Gemorah.