He can't handle not being there for her.
She knows he can't always be there to save her from her demons.
He thinks he is her one and only but in reality, he isn't the only one wanting her.
She knows she needs to choose but she can't one is sweet and is her best friend and the other is her boyfriend and everyone knows that they like each other but people ask if they are friends with benefits. She knows if she breaks her boyfriend then her best friend will be scared that she will break him.  She wants to choose her boyfriend but her best friend is a sweet temptation. Her boyfriend acts like he wants her but never actually spends time with her.