Please note that this story is set in a modern world.
First off, the story involved a main male lead who was some sort of dark mage and described as "unkempt" or "wild", a complete opposite to the main female lead who liked cleanliness. Which, because of that, made her female friend doubtful the female lead would be attracted to the male lead.
Another thing I remember: The male lead held certain tattoos or runes on his body that acted as hot keys for certain magic spells, enabling him to cast certain spells instantly. I think he used a teleportation spell in front of the female lead, making her impressed since that is a pretty difficult spell to execute.
The female lead, I think, worked at a magical library that held numerous grimoires. Also, I recall that the girl friend of the female lead had romantic interest in a very cold, indifferent male Angel.
Last, the male lead had a infamous dark mage enemy who plotted to use the female lead against him.