Can anyone recommend me a romance manga with a black long hair female lead with a beautiful guy lead?

orange marmalade, perhaps?
not sure if the guy counts as "beautiful" because he's not really drawn in typical japanese bishounen style as it's a manhwa/webtoon, but he's definitely not bad looking.

hmm... you could try Tasogare Otome x Amnesia she's gorgeous and I'd say the guy is not bad.

Edit: And I second Orange Marmalade. It's a very good webtoon.

Yes, you're worthy!

How about Kimi ni Todoke? The girl has long black hair and is known for being scary-looking, while the guy is popular and good-looking. I don't know if he qualifies as a bishounen, though.