YES PLEASE
I was never into food in any romantic or sexual way, though I didn't mind it either, but since food is such a theme in MP100 and the fact that Mob does casually feed Reigen in canon makes me go positively insane over tropes like that!!!
I love the casualty about it tbh, but yeah man, I think Reigen should very casually offer food and Mob should very casually accept it and now and then Mob should lick Reigen's fingers clean and un-casual Reigen immediately by it even if that's not at all what he meant to do.
Mob probably would be so oblivious to it anyway. He gives his fingers a lick, then gently sucks on them for just a moment & Reigen has to keep it together.