try using the ideas you already have.. why don't you try to combine them.
Girl moves to london where she befriends a kind boy who tells her the most fantastical adventure stories, she starts to fall in love with him, and begins to truly trust him. one day he tells her that there are people after them both, they need to run or they'll be killed along with their families. she believes him, they go on the run together for weeks, maybe even months, their feelings of affection for each other grow... they are finally caught by police, the girl obeys them cops quietly until she see's te boy fighting, kicking, and screaming, "No! don't listen to them! don't go with them! they'll hurt you! they'll Kill you!" the girl starts to fight and has to be restrained. when she wakes up in a hospital, where she is finally informed that the boy was mad, that he had been ever since he had witnessed the murder of his father and little brother 13 years ago. he suffered from schizophrenia, the paranoia it induced had caused him to make up the whole threat that had forced them on their "adventure" he had never meant to deceive her, but in his insanity he truly believed, and had convinced her of the dangers around them. with that in mind she sets out to see him again, knowing she will find him in a ward for the mentally insane... and realizing that she doesn't care.
she still loves him.
