Shijou Saikyou no Deshi Kenichi, Rosario to Vampire Recommendations
"History's Strongest Disciple Kenich"i isn't with vampires, but the style of the story is the same. They're both in the same style of comedy, there is a boy who doesn't know anything about a topic but anyway has to lern fighting against enemies. The girl, who he loves, is very good at fighting and always helps him if he get attacked. Anyway, the parents don't know about that exactly and the boy has to stay in the doyo.
It's a very funny story and ends up the same way.