Leap of Love/Harems
In Leap of love there are multiple harems you can achieve. One of them is the Ultimate Harem, with all seven princesses.
Story guide
Step 1: You need to refuse Orcus's request in the Jezebel's path.
Step 2: Go to the library in the Balam's quests to learn how to fight Orcus.
Step 3:
You need at least 30 in Prowess, Knowledge and Charm.
You need the Amulett of Lupercus (Calista's Path) and the Solar Protectus (Violaine Path)
You have to complete the paths of Alienor, Blanche, Charlotte and Diane ( can be via the harem with all four of them )
Go to the cave in the afternoon.
Step 4: Before the wedding, you must have completed Violaine's path and Calista's path.
(You can now marry all princesses)