Is this Lust?

She was the first, and the only, person he had ever lusted after, and she just so happened to be the only one he couldn't ever have. Naturally, he had to make do with others. His 'group' called them slags, and it's not like he cares for any of them, so he doesn't even bother trying to defend them. She isn't a random slag though. She may be a mudblood, but never a slag.