I know the conventional wisdom is, “Write What You Know” but I think this can be interpreted very broadly. You may not have lost your entire family in war, for example, but most of us have experienced painful loss–the death of a friend or relative, or even a beloved pet. You may never have been “in love” but you’ve probably seen people around you (parents, older friends, siblings, even just characters in a book or movie) in close, romantic relationships that give you a taste of something you hope to experience one day. But, as @literatureforthelight said, a story for young teenagers doesn’t really need a heavy romantic element anyway. There aren’t many 14-15 year olds making lifelong commitments to each other these days…which is where the real romance comes in.