Help on making a Romantic Villain?

I finally put the main villain into the story, but first I want him to get all buddy-buddy with the female MC. So do you guys have ideas that will make the readers and the MC like him while he's annoying the main love-Interest that very protective about the MC?

Well…you could give him a SWEET personality (whether its real or not is up to you) like I'm talkin CINNAMON ROLL sweet.
Just a thought

That will be a little hard since the first thing he did was accuse her of killing his pet… Which she did… but she lied about it… But ill try :)

And… What about annoying the Love-interest because this guys is so way better then him?

Well…if your MC hangs out with Baddy more than LI then that should be pretty annoyin. Especially if they make plans without him.
Another thing to do would be to have one be SUPER talkative.

Tsukiyama Shuu from Tokyo Ghoul would fit this pretty nicely. He was a villain for some of the first season, but damn, he was fine. His culture and mutual bibliophilia attracted Kaneki's (the MC's) attention, similarly to Rize. But Touka (eventual MC love interest) was permanently ticked off with Tsukiyama.
Also, Tsikiyama's French, and that's always an advantage.