what happens if someone's soulmate dies young?
Lore questions like this honestly give me life on the inside.
Basically it doesn’t matter so much when someone’s soulmate dies - it’s not as though nature really gives people new soulmates or changes names after all - as much as what happens when someone’s soulmate dies.
If you happen to already have a bond to someone - less likely when you’re both younger but not impossible - the loss of that partner can strain your mental and physical health. It won’t necessarily kill you, exactly, unless you weren’t in good health already or you happen to grieve especially hard after a lost partner. But you’d definitely be more prone towards depression and sadness and a kind of bone-deep longing, I’d imagine. After all, you used to share a very close bond to someone and now that’s gone and you’re always aware there’s a hole there, you’re just more aware of it sometimes than others.
Conversely, if you don’t already have that bond established (whether because true names haven’t appeared and/or you simply haven’t made an emotional connection long or strong enough to start a bond), you might still be subject to some increased risk for depression, but to a far lesser degree. You never bonded, so you could conceivably go your entire life without ever really consciously realizing your bonded is dead, though you might get suspicious if you never really feel a pull to go anywhere to find your soulmate or if that tug just flat out disappears one day. Some people go their whole lives without finding their partner, so it’s entirely possible that you could never know.
Of course, as you might imagine, having a polybond would potentially mitigate the symptoms (since you would have the hole still but you wouldn’t have quite as large of an absence, if that makes sense) and would help stabilize. And similarly, if you sever the bond and replace it with a name of your own deciding, you could also alleviate any symptoms that might be caused, which is something that would be possible at any age. Hell, some people whose soulmates have died probably sever and bond with each other so they can have some kind of bond rather than none at all.