I don't know...is it? ;)

Beyond individual sentiment, though, there are a few things to consider given age and era.

First, few medieval girls got married so young. Later data, when we have better surviving baptism and marriage records to compare, suggests that rural women did get married younger than urban women, but late teens or early twenties might be more likely. (For England, Judith Bennett posits that most rural women and men would be married by their early twenties, but this number is "suggestive, not determinative.")

Second, not all women (who did not go into religious life) got married! Once again, this decision is more associated with women in towns or cities than villages--scholars have estimated anywhere from 10% to 25% of urban women were single. Scattered surviving records (mostly from 14C onward) show that among wealthier peasants, it was not entirely unusual for teenage boys and girls to inherit some property and/or start earning income even before marriage.

Third, in the 13th century, immigration to towns was becoming more of an option. Obviously this made up a tiny portion of the population, but it was significant enough to keep towns growing despite them being what we call a "population sink." (More people native to the city dying every year than were born there).

We know that a lot of young women and men who did move, did so at least in part to earn either dowries or a sum to help set up a household.

Another benefit here might be a larger pool of potential spouses, but perhaps not. For people working as servants or apprentices, employers often tried (note: tried) to have some say over employees' marriages.

I'm not entirely sure what that situation says about excitement over marriage, but it does suggest people who knew they were going to get married trying to exercise control over the situation to have a more positive experience.

Fourth, in the 13th century, religious life (including single/of chastity) was also becoming more of an option for women outside the richer classes, although immigration to a city would probably be a factor. In general, we think of these women as "beguines," although that's more of an informal term at this point in time.

They did not live in a formal monastery or take the permanent vows of nuns, but they did pledge themselves to lives of chastity and charity. (Although it was also possible to leave the beguine life and get married.)

The draw of this informal religious life to some urban women and girls suggests it also existed among rural women and girls, at least to some degree. They probably had less access to the preaching and teaching that might help inspire such goals.

(My username comes from the writing of a 13th century German beguine!)

Fifth, there is the family situation. Scholars have often framed marriage for women as moving from the authority of the father to the authority of the husband. Obviously there are a lot of individual factors in play here.

Sixth, love and sex.

...But those are probably up to you.