main scenarios based on the fact that its own since its known she waits for him every day
1. Likely adopted
2. She drugged him cus of his cowardice and took multiple steps ahead. He isnt a virgin but he doesnt know that
Worst case scenarios
1. She met someone while waiting for him in those two years
2. She isnt the kind of person she actually is, haunting the narrative but is actually the worst person he's waiting for. We've only seen just a few panels of her but they're both pretty honest with eachother.
Its pretty stupid lol, but likely Haruka is a girl she found in the dungeons while waiting. After deciding that waiting would take too long she might have decided to dive into the dungeon herself since the narrative still revolves around dungeon diving