Everything about him was poisonous, his looks, his power and, most of all, his magic.
And yet, she knew she would never want him to change, because, for her, he was perfect just the way he was, with this emotionless, dangerous, intoxicating way of doing magic.
If you had asked her whether this was a love story she would have told you that she knew he wasn't capable of loving and he knew she wasn't going to try and change him.
And yet, if you had asked her whether this was a love story she would have told you that the answer depends on what you expect.
She knew that he couldn't love,
she accepted that he didn't care,
but she would die to make him understand.
Voldemort intended the object to be used by his most loyal follower in the event that his horcruxes were destroyed, but it ended up in Hermione's possession instead.
She knows she has to kill him. Steal his horcruxes. Destroy him. But Tom Riddle isn't who she thought he was. Hermione discovers it's a dark descent into the madness of the man she should hate, but can't. When she realizes Tom Riddle's soul is half of her own, she knows she can't destroy him.
To kill him would be to destroy herself.
There simply has to be another way.