A question about what seems to be れいせい & its usage


What is the context of the video below (from 1:18 to 1:26), especially the
word 「れいせい」's meaning in it?

<https://youtu.be/ehSCmkVVjlg?t=78> (try using a VPN if you can't load the
video)

For the time being, I'm guessing that it is 励精, based on the vague content
that I have picked up on, but I still couldn't understand how it's used in
such a way.

Thank you for your answers!




It's 冷静.

> **A** : あー、なっちゃんと同棲だなんてー、うふふっ。  
>  **B** : だから、ただのルームシェアでしょ？  
>  **A** : 事実上、新婚生活ってことだよね？  
>  **B** : …何言ってんの？  
>  **A** : あ、まったりするのもいいけど、早く準備しないと講義に遅れちゃうよ？  
>  **B** : 冷静なの！？  
>  **A** : 大好きなの！

I think the last two lines are hard even for native speakers to follow, but
these probably imply something like "How can you be calm (like that, after
saying such embarrassing things)?" and "I love you (so I'm not calm now)!".

I haven't even seen the word 励精, so you can forget this possibility.

