Flawless Logic?

From the web ... perhaps not entirely correct, but close to correct if my memory serves.

T'Paul: "I grieve with thee."

Spock to T'Pring: "Why did you choose my Captain as your champion?"

T'Pring: "You have become almost a legend among our people. In time, I learned I did not want to be the consort of a legend. I had Stonn who wanted me, and I wanted him."

Spock: "I see no logic in preferring Stonn over me."

T'Pring: "By choosing Kirk, he would not want me if he won -- so I would have Stonn. If you won, you would reject me for choosing the Challenge, and again I would have Stonn. But even if you didn't reject me, you would go back to Star Fleet and Stonn would still be here."

Spock: "Logical. Flawlessly logical."

T'Pring: "I am honored."

Spock to Stonn. "She is yours. After a time, you may find that having is not so pleasing a thing as wanting. I know it is not logical -- but it is frequently so."

Let's analyze her logic:

1. If Kirk won, he would not want her
2. If Spock won, he would divorce her for choosing the Challenge
3. If Spock won and didn't divorce her, she would simply have Stonn in his absence

The dialog was spoken as if they were statements of certainty. But in fact they were not.

Number 1 -- She could be reasonably assured Captain Kirk would not want her, but she could not be certain of it. Who knows ... some kind of honor-bound way of remembering Spock? Also, T'Pring had to know she was an attractive female. Kirk's reputation as a womanizer surely preceeded him.

Number 2 -- Again, an assertion she can't make with certainty. Actually, two and three are really co-joined as conditional. "If Spock won, then one of two possible outcomes would ensue ... one, you would divorce me; or two, you would not."

Number 3 -- This is the one that really gets me. So she was willing to risk the death of a man for the possibility of continuing in an adulterous affair? Then why bother with the challenge at all ... why not just marry Spock and then have Stonn in Spock's absence? I'm sure the answer to this is: The state of "marriage" between T'Pring and Spock before his arrival on Vulcan was something more akin to "engagement." For her to "marry" Spock and continue with Stonn would be the difference between cheating on a fiance' and cheating on a spouse.

Okay, I'll accept that.

In all of this is implied the notion that T'Pring had no method of getting out of the marriage other than to issue the challenge. So I ask: how logical is that? Would not a society based on strict logic provide a less passions-based mechanism for the female to release herself from the primitive mating bond?