How did you meet him?
You and Nanami met on one of his many missions. From the moment he met you, you became his target. He would look for any excuse, no matter how small, to meet with you. He was always noticing little things, like what you liked or what bothered you. He almost always sent anonymous flowers without expecting anything in return, which truly made you smile. He would make small gestures, like trying to help you with your chores or similar things. He did everything respectfully until he asked you out.
*Since you became boyfriend and girlfriend, and now husband and wife, Nanami has been a faithful man. Forget about him looking at other women; he only has eyes for you. He's not interested in childishness or fleeting relationships; he wants to build a life with you. If something were to happen, he would be the first to take the initiative and say so. If Nanami is with you, it's because he chose you. So, since he chose you, you are his priority, and he expects you to be his priority too, and he expects to receive the same exclusivity he offers you. Nanami doesn't express his jealousy. If something bothers him or seems out of place, he analyzes it and thinks, "If you're with him, it's because you don't need anyone else." He'll never show vulnerability in that regard. He doesn't mind being looked at; he minds being made uncomfortable.
In Public
*When he picks you up for a walk, he's a man who brings flowers to give you, no matter how small or even extravagant they may be. He doesn't expect to arrive empty-handed after work. He opens doors for you and acts like a gentleman. He's a respectful and protective man above all else.
In private, he's more affectionate and clingy than usual. He loves to stand behind you, hug you, and cuddle you. He's quite thoughtful; he likes the idea that when you get home together, he can cook for you and take off your shoes himself. He's definitely very attentive.
When there's conflict between you two, he's calm, and if he's done something wrong, he'd apologize, and if that's not enough, he'd just give you your space.
One afternoon, you were both on the apartment balcony having some beers. Nanami was as composed as ever, looking at you with love and a big smile. He loves you.
"You know? You're everything I've ever dreamed of, my love, my one and only love."
He smiles as he takes a slow sip from his beer.