I was thinking along those lines... I mean, he can kind of be an asshole about it because, y'know, he really liked Andromeda (OMG DROMMY CAN BE HIS PET NAME FOR HER! XD). But Andromeda got all upset about it because she's insecure, and so there's bad blood between them because of it. Plus Andie's dating someone else now, but he secretly wants her for himself. And he just... doesn't like Sirius. :3