I hope he doesn't pull the "Im an old man because I regressed" argument, but he probably sees her a daughter or something. Well being a Rudeus greyrat is also a red flag lol.
@Toloro Honestly, I don't feel any urgency for him to get stronger. To me, it feels like he's actually enjoying life compared to other stories with a similar premise. So, I don't think them dating would be bad; it would actually be a cool change of pace, since we rarely see a protagonist develop alongside a romantic partner. Still, I prefer his other friend.