For me, there's seems to be so many unspoken issues of both the individuals and their relationship. One is that there seems to be an insecurity issue for the girl that's why she keeps on inventing names and personalities. Second is the true feelings of the guy for the girl whether he really loves her or not. I'm not really sure what their relationship is. They could be boyfriend/girlfriend, just friends, or friends with benefits but what I see is that the girl really loves the guy but the guy seems to still have feelings for Beth/his ex girlfriend. So that makes things complicated for them.
If it were up to me, I would end the story in a way that the girl, after the phone call, would realize that the guy whom she loves is in love with somebody else and that she would just disappear from the guys life to maintain the "mysterious" tone of the story. No explanations, no closures, no nothing. She would just make a silent exit and then it would just hit the guy that she left him. For good.