50NL, 100bb deep
Folded to me OTB, I PFR 4x with, a nitty TAG 3bets to 13bb total in BB, I call
Flop comes
He checks, I check behind
Turn comes
He bets 15bbs, I call
River comes
He bets 30bbs and it really feels like I'm up against solely AA here. Can I ever be justified in flatting?