Hmm...well, even causing despair isn't inherently a bad thing all the time. Causing despair for despair's own sake is worthless, of course, but without despair, hope couldn't exist. It wouldn't even be necessary, and people could hardly perceive it without something to contrast it against. Overcoming despair is where the most powerful hope comes from, after all.

So even in your example...you'll have created hope for one party, and while the second may feel despair, I think it would have to be the kind of despair from which there's no recovery before that hope you create would be cancelled out! Eventually, the very act of finding hope and meaning even in the face of their grief may be a form of hope you create in that second party.