The answer is that a man who sees such strife between a husband and wife should abstain from wine because he too may become involved in similar affairs, and often through wine. However, this is not a good reason because, in that case, Sotah should come first, and then Nazir. Rather, the connection is more roundabout: in Ketubot (Dowry), we mentioned one who vows in regard to his wife, from there, we went to discuss Vows (Nedarim) and then Nazir, which is a type of vow, and finally, we are back to Sotah, just as we said before, but in a different order.
In truth, man should blame himself for any marital trouble since the wife one deserves is in proportion to his own good qualities; in general, finding the right spouse is as hard in the eyes of God as splitting the Red Sea. But why should it be so hard? We know that the spouse is predestined for every person when he or she is born!? - When we say that it is hard, we mean the second marriage.
Art: Portrait of a Couple by French Unknown Masters