Poor Hinata with the self-doubt.
I think it's a bit more than self-doubt. Well, it looks like she doesn't have much self-esteem here, but the actual problem runs way deeper than being pessimistic or selling herself short. Hinata had a very bad upbringing, she was neglected and probably even violated and abused by her overly obsessive mother. And most likely from early age on she was told she's worthless trash, a nuisance and treated with hate and disdain. She got told she was bad and believed it, because good girls won't get punished - her life was essentially nothing but hellish torture...
It was under those circumstances that Hinata developed her adaptive "good girl" persona - she does not want to be alone, end up disliked (or even hated and ostracized). Natsuki Hinata is what you call a good pretender in a great disguise, and she is also fearing to be or become like her abusive mother - a woman who was most likely an overly possessive yandere, the worst kind of parent you could imagine and maybe (but that's just my theory) even a criminal. That's also part of the reason why Hinata does not want children.
It's still a few chapters down the road, but Sumire is spot on when she called the seemingly indifferent Hinata the weirdest woman among Sou's guards.
To heal Hinata's childhood trauma she needs great care and a lot of love. If she could have Sou for herself, which is impossible, she might feel loved for the first time. But the problem here is that pretty much every girl around her wants Sou. Healing Hinata's scars under those circumstances is not an easy mission. And going at it the wrong way might lead to a desaster. Luckily enough this is not some psycho-horror show, so we will probably not see Hinata wielding a bloody knife. Well, unless she slices up raw meat for cooking or something.