Hey, this sounds pretty harsh but sometimes people are just dealt the wrong cards. Listen to your friend, she cares about you enough to tell you the harsh truth, which is the most valuable truth of all. If you do decide to move one, let whoever you move on to know about your conditions. I can only imagine how horrible it must be to be diagnosed with a brain tumor, but it's something hard on not only you, but to those who are close to you.
They have to know that things could happen. I know many people dont like to talk about it, but things CAN happen. Maybe that is the boy's problem, he's scared so he distances himself. Though, I dont know anything about this boy but from what your friend says, you may just need to move on with your life. Find new happiness.