Loneliness conquers everyone eventually. It sweeps over us like a wave. Life on a hell mouth is like this. An un-worldly force intensifies emotions and darkness fills all living things filling them with pain, anger and hatred. Demonic activities are common. All sorts of dark creatures are attracted to it.
Before moving to Sunnydale Buffy Summers had been happy. After becoming the slayer all she knew was loss. She had seen many die and failed to save many. She had loved many and lost more. Her heart was broken so often it could not be fixed. She grew distant from her friends, fearing she would endanger them. Her friends had done so much for her. Risked their lives many times.
She stepped forward. She had climbed to the top of the old tower and had opened the antique window. She climbed on to the window's edge. She was calm. She blamed no one for this. Only herself.
It had been 5 years since she had left Sunnydale in ruin. Willow, Xander and Dawn were long gone. They could now live normal lives. She wanted to be rid of her responsibilities. She refused to die by the hand of evil. She had died before and knew she could go to hell, but to her life was hell. She had given up on life.
She took a deep breath, closed her eyes and stepped into the air. She accepted death.