1010 (or one of them, if you don't want to do all) with a bodyguard S/O that hasn't fully confessed and is (poorly) denying their feelings?
Rin: He's really good at telling when people are simping, so he knows. Boy oh boy will he tease you every chance he gets. Sometimes that's disguised as getting you near him, asking you to guard him at places and it's just the two of you. Other times it's blatant flirting, showering you in compliments, teasing you whenever you seem shy, or throwing a wink your way.
But he isn't sure that you really want to be with him, that maybe you're just dazzled by him, and since your relationship is supposed to be professional, he doesn't want to do anything too much and make things awkward between you. So he tones it down sometimes. And being around him so much, you get to see him when he's tired, how he acts before shows, chatting with his brothers. He doesn't always need or want to be in performance mode, so both because he wants you to see his normal self and because he needs to, you get to be with not-flirty Rin. And he thinks that if you can be with him in those moments and still have feelings, maybe there is hope in dating you.
He never really approaches you seriously about it though, letting you decide if you really want to. So if you're shy about it, it's going to be a long time, or it's going to take one of the other boys getting you two to talk to each other. He does address his concerns about dating with you when you confess - you know he's not always as perfect as he is on stage, he'll be busy a lot and so will you, you both need to be careful about publicity...but he also gets a little flustered himself, letting you know that all those times he wanted to be near you and flirted with you, he meant it.
Purl-Hew: For a while he really thinks the reason you keep staring at him is just making sure he's okay, and your blushing is just heat or stress. But it doesn't take long for him to notice how your behavior in general, staying constant, indicates you've got feelings. Although he's given you compliments before, he doesn't really start flirting with you until he suspects you've got a crush. He's fairly subtle about it, with little things like praise, nicknames, fixing your outfit a little, but he does it quite a bit, just to see how you react. Both to judge your feelings and because he thinks you're cute when you become a mess.
With how much you try to deny your feelings, he figures he’ll have to make the first move. He thinks on it a while, and feels confident that he can keep a relationship hidden from the public. When he’s able to be alone with you, he’ll ask you, seriously, if you’d like to date him. And when you say yes, he smiles brightly and admits that he’s had a crush on you for a while too.
Zimelu: He has an “I don’t need a bodyguard“ attitude at first, but as he grows fond of you he loses that for appreciating your company. He first sees your acting differently around him as stress, and starts showing off and talking about how tough and capable he is, hoping it will ease your worries about your job.
When he catches on to your obvious feelings, though, he internally freaks out. He starts getting a bit short with you at times because of that. But if his attitude troubles you that you’re not getting along and he finds out, he’ll take a moment to tell you, seriously, that you’re doing a good job, and he likes having you around.
As he accepts that this is happening and gets more comfy with the possibility of dating you, he actually gets excited and almost confesses himself, but he decides to see if you do first. And if you don’t soon enough, then he’ll confess to you.
Haym: Immediately catches on and thinks you’re the cutest thing. He’ll sometimes tell you about stories he’s read or movies he’s seen where the bodyguard and the person they’re protecting fall in love, or similar situations. It’s his not so subtle way of saying he likes you too and it’s okay to confess.
He’s had an eye for you for a while but didn’t want to make you uncomfortable. So now that he knows you like him too, he’s just flirting with you all the time. And making excuses for you to spend more time with him. He wonders how different you might act once you two have both confessed.
If you happen to confess first, he laughs about how long it took and tells you he’d been waiting for when you’re ready to confess how he feels. Or if he happens to confess first, he tells you he wants you to relax around him, because you seem stressed about admitting what‘s on your mind.
Eloni: Can‘t believe you have a crush on him, although it becomes clear with how you act. He would think you’re joking, except your reactions are so genuine. He soon mentions it to his brothers, whose responses are basically “Yeah no shit they’re obvious” And of course they tease him about if he likes you back...He thinks on it until he realizes that yes, he likes you, and not just because you like him, and he wants to date you.
Youre practically dating even before there are any confessions, as Eloni asks you to spend more time with him than just keeping watch over him. He likes your company, and once he realizes he likes you back, he’s testing the waters of if you two do alright outside of your duty.
He gets nervous about jumping in to confessing, so it’s a long wait to whichever of you confesses first, or perhaps some intervention from someone else to get you two alone and to confess.