CO is 33/26/4 over 150 hands samples.

flop : kinda range check spot for me.
turn : I think its no choice but xc with a pair, double gut and FD vs nearly pot bet.
river : I snapped vs 80ish bet in reality. But need to take time more for sure...

I thought his big bet looks so strong and my worst flush would be beaten often against his Ahi/Khi Flush. But his 75/nearly pot/80 line is bit suspicious in hindsight. I don't think weaker players would bet like pot size with FD. Maybe AThh/KThh. Set/2pair/OP(I didn't think he would have over pair at the time, though.) are much more natural. Yeah I don't think weaker player would pot bet w naked FD often. And his river size would definitely reduce some Flush combos.
I feel like its a blunder now...What do you guys think this spot?