You
do not need to view the neutral/bad/solo endings
Raymond:
Laeticia:
and you
do not need to save after viewing the endings. I only saved after the initial run for the file clear star to access the post-game dungeons, and this achievement locked alongside the one for my final ending.
Only the character with the highest affection will get an ending with your chosen lead. This means that you have to complete the full game twice, choosing Raymond and Laeticia at the start of two different saves, and kill the final boss at least 16 times in total. The item
Tears of Aphrodite will increase a character's affection with your lead and will be your go-to source for acquiring different endings.
You'll receive one
Tears of Aphrodite by turning in Mini-Bunnies, and a second can be obtained from a chest in the final dungeon of the main game. To acquire more you can either farm bosses (the frog, specifically) in
Den'mohr Delve - which you'll be doing anyway to get money for Item Creation - or through Compounding (
Aquaberries +
Roly-Poly Bean) using a character such as Nina. Unlocking talents like Blessing of Mana may or may not influence the rate at which the item is created; save and reload as necessary.
Only a handful of
Tears of Aphrodite are required; aim for 5~10, then save. Give them all to one character, kill the final boss, decline to save, then load and repeat with a different character.