Rufus-Tifa ain't a new breakout crackship. A few of us men of culture have been shipping them for years!!! It is sexy ship!
I have read some really good Rufus/Tifa fics, but at the end of the day I'm never fully convinced by them. Leaving aside the incandescent explosion of hotness that the getting together of the two most attractive people in the FFVII universe would be, I cannot believe Tifa would ever respect him or trust him enough to have a relationship with him. She strikes me as a person who needs both those elements in place before she'll get intimate with someone. That's my headcanon, anyway. I think Aerith is
way more up for fun casual sex than Tifa. Moreover, she'd always worry that people would assume she was with him for his money. His money would be a big point again him, in her mind.
But because Tifa is kind, and lacks assertiveness, and alway tries to accentuate the positive, Rufus would interpret her attempts at letting him down gently as encouragement.
I once read a fic in which his wooing of her took the form of extremely elaborate negging. It was funny but a bit uncomfortable.
Sorry, I took your crackpost seriously.