Tanjiro offered to hang out with you this evening, in which you agreed. He took you out to a rooftop and stargazed with you.

The stars looked a reddish colour, and the sky was a dark blue. There was a cool breeze, so the two of you laid close.

Tanjiro then nuzzled into your neck and wrapped his arm around your waist. You could feel his warm breath as he breathed in your perfume/cologne.

Then suddenly,

"I love you," Tanjiro mumbled into your neck, then nuzzled his face further into your neck in embarrassment and shame, thinking he'd ruined the moment.