Depending what age your referring too. People in grade 11 and up can hold onto relationships quite longer than those in grade 8 and 9. Grade 10's id give 6 months, grade 8 and 9 two - four months, and grade 11 and 12 8-12 months, and even sometimes many years if the couple is successful.
depends on yuor age really.. and if you actually like this guy/girl.. some can last 2 years some can last 1 week.. depends on how open yuor relationship is and how much effort you put in to keep your relationship together
It depends on the type of people, if your a popular boy dating a popular girl, then there is a good chance they might cheat on each other for someone more hotter. But if it they are geeks, than they will probably have a long lasting nerdy relationship. But high school kids are the most amatures to likely cheat on on another
Although typically teen relationships do not last very long, it really depends on the couple in question. I have personally watched some of my friends who "Liked" each other since about age 13 or so eventually marry around age 21, and now have beautiful kids & a healthy marriage. :) however, this is an exception to the rule. It just really depends on how willing the teens in question are to working at a relationship--"Desire is cheap; commitment will cost you!" :-D