@Taegyu
it's passive aggression, she was jealous of him so she was giving him back handed compliments. The "omg I love ur choker!" Is supposed to be condescending and point out the fact he's an omega which she considers to be inferior. People in real life will do this, "omg that outfit on you is so nice I could never wear that!" for example.
Moral of the story, don't take every compliment at face value. (Esp if u and the person ur talking to are both girls lol)