Well then, we disagree. I think highschool relationships are entirely unecessary, and, more often than not, harmful, and I have seen a ton of them. Neither of may parents had any major relationships in higschool, and they are now celebrating their 27 Anniversary.
As for kissing, Siberian, the Catechism says that as long as you do not specifically provoke sexual tendencies, it is alright. And also, if it happens by accident becasue you gave her a hug or something, that is alright as well. But if you do it on purpose, outside of marriage, that is wrong.
That would be the Catholic point of view.