Title:
Nice. Not cliche and not too complicated. I understood the aspect of rebels since you spoke of Cole been a troublemaker but the aspects of the clause I didn't see it in the blurb. But it's okay as long as you show it in the story.
Cover:
It doesn't reflect the story not at all dear. I know you spoke of Christmas and that is why you have chosen to put reindeer on it, but the colour you have chosen on the cover, makes it quite impossible to actually notice it and even if, it doesn't give any advantage in attracting your reader. It will be preferable if you either show a boy and a girl in the snow seated, playing or walking or even by the coffee shop. If you insist on reflecting the aspect of Christmas, then show a Christmas tree and make the title bog enough. Spread some amazing colours and that will benefit your story more.
Blurb:
Quite short, but in this case I think it's okay. You introduced us to the portaginst and showed us their point of conflict.
General View:
There is a good flow in the way characters interact. When you read it, it is easy to understand with not too big vocabulary and with minimal spelling and grammar error which is good. Also, your description is just perfect not too big and not to monotonous which is okay. You give us also a glimpse of thier character trait with poppy being a talker and her friend quite a listener.
It is good that you introduced us to Cole earlier of. It makes us reader to get use to them both. You see when someone reads your story, he should either extremely love your portaginst or hate your antagonist depending on what your story talks about and that can only be felt when the reader is introduced to the main character earlier. When a reader has no connection with them or it takes too many chapters to meet the main characters, it will cause them to shrug and just drop the story so it is good to bring both of your characters to us in the first ten chapters. Or if not, talk about them. Tell us that two years ago this happen or that happened if you want to keep suspense.
However, the way the story flows after the third chapter is quite if not to say cliche I will rather easy to guess. He sleeps across her room, finds her a pet name, her parents will ask her to take him along with her, parents will continuously put them together and then we can see they will fall in love. If you weren't as far I to your number of chapters I would have advice you to look for another way. However it is not bad. Everyone has its own way of writing and that doesn't make the story less interesting. Cole is funny. You described him as a troublemaker, but I find him rather sweet. And they really have a bound. They have little cute circumstances. As from chapter thirteen, I finally understood why you had chosen that cover due to the stolen reindeer issue. Still, my advice of looking a more catching cover still hold. Maybe this time you can have a girl, boy and a reindeer. But I don't see the essence of bringing the death Santa part. It has no link in my opinion, but maybe in upcoming chapters, it will mean something.
Apart from that, I have nothing to add. Your story is a cute short story for that who love Christmas romance