Oops - late again. Sorry - everyone already answered the stuff I addressed in my last post so it must've looked like I was bringing it up for nothing.
That's right on bullshit. I'd kill a man who left to "protect me". Maybe it's the way I am but I consider a man a coward he runs away instead of standing to protect the ones he says he loves.
A lot of the things people do out of love are, well, selfish. Even if you give up your life for someone you love, it could be argued you did it for a selfish reason (such as you didn't want to live without him/her - or you didn't want to live with the thought that you COULD have done something to save him/her, but did nothing).
Anyway what I'm trying to say is - Cloud is being selfish here, I think. Maybe he figured "Oh, shit - if Tifa (and the kids) know I've got geostigma and that I'm definitely gonna die, they're gonna be shit depressed until I kick the bucket, and thereafter to boot. But if I just stay quiet, make them think I left because I cba to stay with them, they'll just be annoyed and hurt (which is loads better than worrying about my impending doom). Oh, and I thought I could save Denzel... Only I can't... can't... look... at them... *cries*"