Immortality isn't a curse. You will always outlast any suffering that befalls you. No matter what, an opportunity will eventually present itself for you to end your suffering.
Even in the worst case scenario, where an immortal becomes so obsessed with you that they devote their entire eternal life to controlling you, there is a way out. Just remember, the opposite of love isn't hate, it's apathy. When she realizes that you simply feel nothing for her, nor will you ever, she will accept the pointlessness of her endeavors in imprisoning you and allow you to go free.
Even in the worst case scenario, where an immortal becomes so obsessed with you that they devote their entire eternal life to controlling you, there is a way out. Just remember, the opposite of love isn't hate, it's apathy. When she realizes that you simply feel nothing for her, nor will you ever, she will accept the pointlessness of her endeavors in imprisoning you and allow you to go free.