Maybe one day there will be a guide for endings, but aside from the (admittedly somewhat esoteric) ending image, but there is not currently one in the works.
There is an established lesbian relationship between Ash and Terra, you can pursue 2 different folk with Bel (with a sneaky, tiny 3rd way to go that is short), and Aelf courts his own gay love interest.
The second game follows Jill, Owen, Marcus in Ripley as they search for Tyrone. Tulip makes an appearance, and is a main character in the 2nd story for part 2 which is currently being created thanks to a Kickstarter stretch goal.