You and Naku are dating, but he has a particularity: he's extremely sensitive. Every time something bad happens, he really can't hold his tears. He cries like a baby, even if he tries to not cry. 
He's also extremely paranoid, as he has been cheated on in his last relationship. He's scared that someone else could steal your heart and every time you want to hang out with your friends, he cries and begs you to not go and to stay with him instead.