Insensitive
Thickheaded, Obtuse
な adjective, noun
If you’re too dull to have feeling, you’re insensitive, or thickheaded.
鈍感 often means someone's not very tuned in to emotions or what's happening around them. It's like they can miss subtle romantic hints or not sense the silent tension in a room.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
あんたって、ほんと鈍感。今はフグの話はしたくないの。それくらい空気を読んでよ。
You are really insensitive. I don’t feel like talking about Fugu right now. Take a hint.