The concept of Yifat Toar is not an easy one to grasp. How can the Torah permit something that the Torah does not approve of, as can clearly be seen from the context of the Parsha?
Rashi brings down chazzal that say: “Since (the Torah) we know the person will anyways transgress so we might as well permit it”.
This reasoning can lead down a slippery slope, for anyone that experiences a difficult Nissayon can say that “I will either way transgress so let’s just make this permissible”.
The Torah is the blueprint of the world and all that exists. If the Torah is telling us here in this specific situation that a person will not be able to withstand the Nissayon then it’s a fact, and it has to be dealt with. It has to be dealt with in a way that the person involved can come out of the situation without sinning.
The Torah has no agenda for people to stumble and sin, to the contrary, we are meant to- and expected to withstand life’s tests.
However, since the Torah made no other exception to this rule, that can teach us that everything else we ever encounter can be overcome; every other challenge and nissayon can be triumphed.
For if this was not the case the Torah would permit whatever nissayin cannot be overcome just as in the case of the Yifat Toar.