Read the article
In this article,“The girl said she thought that after having sex with the boy, the relationship would last. Do girls her age normally think like this?” My question to you is: Do girls her age normally think like this? Also, do you think its appropriate to go into a relationship at your age?
Girls at this age do not usually think like this, but there are some exceptions at times for some people. The sex is not only underage, she could get STDs or even get pregnant, and the rest of her future would be ruined.
It is rather inappropriate to go into a relationship at this age, BUT THERE ARE ALSO SOME EXCEPTIONS. Everyone has different perspectives in what a "relationship" is, so it really depends on how mature you are. But I think it is inappropriate. It is a waste of time and effort and feelings. You should just focus on your studies instead of crying in the end when you break up.