Hello,Portuguese dude.
At first,my english skill is poor.
If you can't understand what I means,please comment.
"...to hanareru" means "leave somebody".
you and somebody think that they have to leave each other.
"...kara hanareru" means "leave somebody or somewhere".
you think that you have to leave somebady,but anyone knows what she(or he) think.
"...to" follow only noun pointing to person.
"...kara" follow noun pointing to person or place.