Here's an idea for you.
Include an option: "Give me part of yourself."
If you have a group of 6, have them write down 9-12 distinct things, or choose that many from a longer list you provide them. "All memories of a loved one". "The color blue." "Your favorite X." Etc. Things that are genuinely a part of who you are. They then put them into a box--and you secretly draw out one for each player, and seal each one in a numbered but otherwise unmarked envelope. You, meanwhile, keep a numbered list of which loss is in which envelope.
Then you give those envelopes to the players, and if they choose to make that sacrifice, they pick one of the numbered envelopes and sign it. You know what's in the envelope, but they don't. You use this. Weave it all through the campaign. Make little moments where a character can feel a sense of loss, but doesn't know why.
And only then do the moments of agony arise, when something actually important relates to what was lost--and the player genuinely doesn't know what it is, because you know, and they "forgot".
Nobody has to take this route. It could end in nothing. But if you have at least one adventurous player seated at your table....I think this could be a really, really cool direction for things to go.