Kakashi Hatake has loved approximately nine people. And he's only confessed maybe twice. These are the feelings he will never disclose.
1. His Father
Of course, he loved his father. Greatly. He was his idol. His hero. Sakumo was the first to hear those cute 'I love you''s from little, toddler Kakashi. And it's among one of the last things Sakumo remembered as he lay limp on the living room floor.
2. Tsunade
He remembered her as the nice, pretty lady who talked with his father a couple times. He grew as bashful as Kakashi could whenever he saw her. Thankfully, Kakashi has forgotten about his little boy crush on her. But, Tsunade hasn't. She thinks of the one time he hugged her legs and declared he would marry her one day every time she sees him. Maybe one day she'll tell him about that. But for now, she'll relish in it for as long as she wants.
3. Obito, Rin, Minato
They were his team. Something he felt resembled a family. He was such a prick back then who always got on Obito for the stupidest things. But, it was one of the only ways he could express his affections, really, without feeling so mushy. On good nights, he dreams of the days they spent walking on missions. Obito would be the hopeless fool in front of Rin and he'd scold Obito for God knows what. Rin and Minato would laugh at their typical antics. He wakes up from those dreams and cries gently while smiling at such bittersweet memories.
4. Naruto, Sasuke, Sakura
The sheer resemblance of Kakashi's old team makes him feel uncomfortable. Especially Naruto. The utter guilt he feels when he sees Sasuke and Naruto bicker. Naruto's boyish crush on Sakura and Sakura's idolization of Sasuke eerily reflect his old team's dynamic. So when he sees how Sasuke is silently begging for help, he tries. He does what he needed when he was Sasuke's age. But, it wasn't enough. Sasuke leaves and he keeps blaming himself for what happened. It was all his fault. He should've done better, he should've done this and that. He picks away at himself. Naruto leaves and he knows that he could've trained Naruto more but chose to focus on Sasuke. He desperately doesn't want Naruto to go. What if he never comes back? It's sad, but Naruto feels like Obito to him. And he wants to bask in his holiness for a little bit longer. Sakura leaves eventually too. By then, it doesn't hurt him as much because he was expecting it. Why wouldn't she leave? Why would she want to learn from a failure as a teacher? A failure at everything? But they all eventually come back and reunite as the old team seven again. His students don't know how much he loves them and how much he revels in their familiar routine. Everyday he looks at the team seven and team minato picture and thanks whatever higher power there is for bringing them into his life.
5. Gai
As much as it pains him to feel so, Gai is like the strange brother he never had. To put it simply, Kakashi loves him, even though he acts so disinterested. And that's that.
Of course, there's probably more people he loves but they don't just come to the top of his head like the eight of them do. There's many others he wanted to love and much more he just likes. Sometimes, he sits and thinks and knows that nature reclaims all, including him. So when his time comes, he'll be late (as usual) to meet everyone over wherever you go when you die. Or his soul will get reborn and he'll meet and grow to love them all over again. And either way, it's a happy ending to such a sad life.