b0b, i don't know if you've ever cared for someone, but i sure have. flarestar is right, if you really care for a person enough you won't want to see them die, your actual nature will be to save their life. But of course this doesn't apply to all people it seems.
If i care for the person enough, and if i think they'd do the same thing for me, then i'd do it. I love my girlfriend, i love my family, i'd do it i think. If they were old though then probably not. Like say if my parents grow up to be like 60, then maybe not. I'm not really sure.
If your worried about them living the rest of their lives in sorrow, then just make sure you say 'I LOVE YOU!!' before you die, that's about all you can do and it will make their lives better for sure :)