Remus finally turned, feeling the other's neediness. "Merlin, Sirius. It isn't that. Are you kidding? It is taking everything in me not to react. I've fancied you since third year and you never even noticed. Or didn't care. But now, now after all this time." Remus said all at once. He took a breath and rubbed his face with his hand. "It's so complicated, Sirius. I never meant for it to get like this. And it's all my fault."

If he weren't a werewolf, he wouldn't have this heightened sense of emotions. If he didn't have that then his mates wouldn't be affected. Then neither Severus nor Sirius would both be attracted to whatever it is Remus was feeling. He was doing it to the both of them.