Answer: Here are some tips for you:
Step-by-step explanation:
Regardless of what grade you're in, I think this might help you.
First of all, a romantic relationship needs to develop. You probably shouldn't start off a romantic story where two people already have some sort of romantic relationship going off the bat. Another thing you need to have is a very emotional storyline. Make sure your story has many emotions to really set that mood. Romance doesn't always play out well, there are ups and downs. For example, an individual could be in love with someone who is already in a relationship, and play it from there. It could be whatever storyline you want, though. One more thing, make sure to add romantic scenes between the two characters and add details to help show the bond growing over time.
My tips might not be the best but I hope I helped at least a little bit!
Also, I recommend asking your teacher for additional help as well.