Shiloh and Jeremy are actually cameos from another game made by GBPatch, called XOXO Droplets, and are both romanceable in that game (as is Nate, the rude guy that yells at you during the Shiloh 'reunion'). If you'd like to learn more about them, I'd suggest playing it (though I believe Jeremy's route requires a purchase, while you can do Shiloh's route for free).