It's not.

[Her lashes are low as she looks back at him, poking the tip of her tongue out to press it playfully against his thumb.]

We both have sex with other people and do that sort of thing. It's just how this place is.

[Even if the thought of Tsurugi kissing someone else or being with someone other than her in any capacity makes her still see red but she won't think about that right now!]

You can kiss me all you want. How lucky for you!