She pretty well loves him, and she's hardly alone. He doesn't need that affection ring at all. See the manga cuts out things like the girl's meetings (and their point of view entirely), where back in the woods they where planing to protect Haruka because he is - in theory - incredibly weak. Which he really is in terms of levels, and that's a problem. He's constantly one hit away from death. He always makes sure that hit doesn't land, but if it did... death. Or a skill he has no resistance against because of the level wall. He's a speed-build/glass cannon who's always casually doing reckless thing after reckless thing only to survive by pure luck. Even when not rushing into danger, he's always doing impulsive things. He's getting scolded etc precisely because they do care, but he doesn't process it at all. There are comments like "What the heck?! Every time I go up to him to thank him, I end up yelling at him instead!" but Haruka's way of speaking/reacting/interpreting everything has a lot to do with that. Haruka is madness, but it doesn't really come across in the manga.
Just as a small example, before he fell in the current dungeon he was looking at renovating the dungeons to live in. When he got yelled at for wanting to live in a dungeon, he was still secretly smoothing the floor as they when through the level and planning his renovations... and he fell.
BTW the plunder skill would require her to kill her target. She can't steal a skill at will. Also unmentioned are the skills she plundered from orcs and goblins... let your imagination guide you. In any case much of the class have feelings for him, and they're all quite grateful to him. He doesn't get it at all.