@muttdoggy isn't wrong, that's along very similar lines to my own train of thought.
I would suggest starting her story on the stage of her grieving. It can be something that triggers after the scene with her and Maria. A moment of weakness for the woman who has stood strong at the front of your hotel from the beginning. Either, she could be missing from the desk when you go downstairs, prompting you to investigate, finding her room for the first time. It could be your grandfther's birthday, or an anniversary of theirs, or it could be the day he died. Regardless, this offers the MC an opportunity to get closer to her, he offers her comfort in her grief. This confrontation could reveal something, maybe something she and your grandfather used to do together, like visit that park we took Ashley to. I wouldn't suggest anywhere we commonly go, like the cafe, that would be for later.
From there you can build, have the MC surprise her by taking her to this location. From there we can allow it to become a recurring event where she slowly comes to trust and enjoy her time with the MC. She could work through her grief by talking about him with you, something she didn't get the opportunity to do with all the other girls choosing to leave. Eventually she can come to the MC, asking for something, or maybe to repay him.
I'm sure from there it wouldn't be too hard to build the whole story.
I would suggest starting her story on the stage of her grieving. It can be something that triggers after the scene with her and Maria. A moment of weakness for the woman who has stood strong at the front of your hotel from the beginning. Either, she could be missing from the desk when you go downstairs, prompting you to investigate, finding her room for the first time. It could be your grandfther's birthday, or an anniversary of theirs, or it could be the day he died. Regardless, this offers the MC an opportunity to get closer to her, he offers her comfort in her grief. This confrontation could reveal something, maybe something she and your grandfather used to do together, like visit that park we took Ashley to. I wouldn't suggest anywhere we commonly go, like the cafe, that would be for later.
From there you can build, have the MC surprise her by taking her to this location. From there we can allow it to become a recurring event where she slowly comes to trust and enjoy her time with the MC. She could work through her grief by talking about him with you, something she didn't get the opportunity to do with all the other girls choosing to leave. Eventually she can come to the MC, asking for something, or maybe to repay him.
I'm sure from there it wouldn't be too hard to build the whole story.