I say it's her future husband, who, after witnessing his wife fall into a coma from an unspecified trigger, makes a deal with a higher being of power to go through Itai-san's memories on order to wake her up again.
This explains the surprise from the Narrator, since if this was her future self, she would already know what happened in her past and wouldn't be surprised (i.e. lying about having a boyfriend).
@justforthelulz Looking back at your old self in bewilderment sounds like normal human behavior, though. Especially if her mindset is very different in the future. Thoughts and actions that may have made sense to her in the past may just be confusing or even painful to her later on.