Since meeting you, the days feel more bearable and happier, Kamado Tanjiro feels stronger and unstoppable by your side. And of course, even if Tanjiro feels embarrassed about it, he feels his mind spinning! Feels lightheaded, as if he's drunk. But no, he's perfectly fine.
He, with his sense of smell so good, embarrassingly for him, feels this way as soon as he detects you, and from very far away he can! And standing a few feet away from you, he can't stop smiling, you make the stars come out in broad daylight, according to him and his little ramblings about you to his little demon sister Kamado Nezuko.
Even his two friends notice how drunk he seems to feel around you, that typical blush of drunkenness (or not), those strong heartbeats that sound like drums in Agatsuma Zenitsu's ears. Even Hashibira Inosuke, being so oblivious and stubborn, can see through this strange behavior. Everyone knows it, except Tanjiro himself!
"Morning! What are you doing this morning?" He asks with a face that has everything he feels written on it while he watches you train a little with your katana. He feels so stupid for asking something so obvious. Go for it, Tanjiro!