Bit confusing as there seam to be 2 posts for the same idea I'll respond to this one.
Firstly when dealing with a romantic vampire movie it must be clearly positioned relative to the numerous romantic vampire movies out already, the shear number of which justify a dedicated genre. This lacks an "angle" or direction for the film by which it will stand out from or fit into the vampire "genre" landscape. Buffy action comedy, Twilight teen sop or Dark Shadow neo realistic farce comedy, etc...
As for the story in the logline it comes across as missing a main character or MC as Karel writes. More like a dual protagonist which is much harder to write as it means they should both share the same journey throughout the story. If this is the case the Logline should reflect it as such which means they both need the same antagonist and obstacles to over come.
But for this you must first decide whether this is a love story, an education plot, a redemption plot etc.
Hope this helps Nir.