Pansy has been screwing Harry Potter for six months now.
She knows it would never have happened if she hadn't abandoned everything she was brought up believing to join the goody-goody Gryffindors. Draco has already tried to kill her five times for her treachery.
But what the hell - she wanted him. And isn't that what Slytherins do? Anything goes in pursuit of what you want.
She's not altogether happy that he won't tell his friends about them. So what if they wouldn't understand, and definitely wouldn't approve? It's his life, isn't it?
But she's given up a lot and risked more to get this far, and she'll take whatever he's willing to give her.