Little lesson here: Acid attacks are commonplace among rejected suitors. They are seen as an 'honour attack' to protect his family/clans honour.
Rejection by a woman is seen as a great dishonour and as such this kind of revenge, although sickening, is not always made into a legal issue.
Now onto Islamic marriages. They do not have the western convention of at least waiting until the woman comes of age. Thats too much of a risk for them. The girl may become 'impure' or find another suitor (maybe from a rival clan for example) in that time. Therefore they pick 'em and marry them young so that they have first dibs on this pure woman.
Thats my understanding of it after watching (being forced to sometimes) muslim courting rituals. This kinda stuff (minus the acid though I could tell you about a firebombing where my girlfriend lives over this kind of thing) happens a lot here we just dont see it because they tend to form miniature versions of their home country in certain areas that are best avoided if you happen to be white or english....