Naruto being a gay one he is fell in love with Kuna when they were 13 or so. Naruto have been always outcasted as being the jinchuriki and so he is thankful to Kuna for being there

Naruto easily gets jealous of anything. Even animals and so. So here he is. Being jealous of a Pillow that Kuna is hugging in the bed

Naruto: "this stupid Pillow." He grumbles under breath with anger and jealousy