Her fight for doing the right thing was part of her fantasy, a coping mechanism. It is implied that she tried to kill herself multiple times in the past. Then she reinvented herself as a never-say-die girl, but she apparently often grew too attached to others (as her father mentioned). Then she got attached to Wally INSTANTLY, his vulnerability being a magnet for her, and it only lasted because he is a great guy. Then the system broke her and her, she lost her safe place and the illusion of who she is fell apart - that's why she commented on Endtown being a big game of pretend. Leaving the town was supposed to let her find herself again, but it did not work. She wanted Wally to shoot Jim and Sarah when they surrendered, remember? This was the first sign that the Holly we knew is but a memory of a person trying to be someone else, someone who had hope. No more illusions to support her, she tried to find a way to cope with the harsh reality, but failed. She talked to Wally about ditching Jim and Sarah, because she was looking for a spark of hope to latch to - hence the talk about future. It was not her trying to find an escape, it was her wanting to believe there is something better waiting. Clive almost set her back on the right track with his self acceptance talk (she still grew way too attached to him, even before Unity) and for a moment she was her old self again, but then Jimgod broke her for good with one short question. She became more aggressive, clingy, relapsed and fell apart, not being able to let go of her past and losing the thing representing the last shard of hope and self acceptance she had, also someone weak to protect (Clive). So given a chance she escaped into another illusion. The chase was her hoping for someone to catch the some other her, some Holly who could be the real her, a better her. But it was all for naught and the sweetest lie of all must end as well.