Why can't I just fold it on flop, only had like 20 hands but he seemed solid .

PokerStars Pot-Limit Omaha Hi/Lo, $0.25 BB (5 handed)

UTG ($43.64)
Hero (MP) ($113.03)
Button ($60.04)
SB ($46.52)
BB ($24.15)

Preflop: Hero is MP with A, 3, A, J
UTG calls $0.25, Hero calls $0.25, 1 fold, SB bets $1.50, BB calls $1.25, UTG calls $1.25, Hero raises to $7.50, SB calls $6, 2 folds

Flop: ($18.25) 6, 9, 8 (2 players)
SB bets $17.34, Hero raises to $51.25, SB calls $21.63 (All-In)

Turn: ($96.19) 9 (2 players, 1 all-in)

River: ($96.19) 8 (2 players, 1 all-in)

Total pot: $96.19 | Rake: $2

Results:
SB had A, 2, 5, 7 (Hi: straight, nine high).
Hero had A, 3, A, J (Hi: two pair, Aces and nines).
Outcome: SB won $94.19