As has been stated in this thread already, she knew Cloud was going through a lot of pain and an identity crisis. She didnt need to blurt out her feelings for him when he already had far too much to handle, and it seems more out of care and courtesy for him that she remains silent. I believe that, if you truly love someone, you think of them first always, even if that means you have to suffer, and I feel Tifa did just that.
Woot!! You go! I'm with you all the way! You are so right. I perfectly agree with you.