Maybe I'm missing something, but Seira is a tsundere? Is that a mistranslation or something? When has Seira ever pretended to not like him or be cold towards him? And her feelings on the inside aren't affectionate like a tsundere, they are obsessive. If anything she is the opposite of a tsundere, warm and affectionate on the outside while internally she's an obsessive, jealous control freak.
Also, the "it's not like I like you or anything" feels completely out of place and out of character.