As teenage love stories go there have been many iterations and for good reason. Teenage films are great because there is always interest in them and they find a market easily so good choice on the genre.
I think the goal for your MC is the love interest, so this could be a boy meets girl story. If so perhaps best to look into the most recent successful films that dealt with teenage love and see what made them work well and what made them original The Fault in Our Stars or Juno come to mind.
What is the inciting incident? By this I mean how does the MC meet the love interest? What is the obstacle? What is keeping the MC and love interest apart?
In this genre specifically, the obstacle is as important as the goal because all love stories are about people meeting each other, what sets the stories apart are the obstacles they need to overcome to be or stay together.
As for the logline best not to mention the title in the logline a strong title could rase expectations for elements that are not in the logline and a weak title may detract from the read of the logline.
Lastly best not to spell out the genre instead let the reader deduct from your story elements what genre it is in, this is added proof that your concept is strong.
Hope this helps.