Good or bad fold?

PokerStars No-Limit Hold'em, $0.50 BB (8 handed) from (Format: FlopTurnRiver)

Hero ($47.65)
Button ($49.25)
SB ($20.15)
BB ($20.65)
UTG ($48.50)
UTG+1 ($54.20)
MP1 ($18.50)
MP2 ($13.85)

Preflop: Hero is CO with 3, 2.
1 fold, UTG+1 calls $0.50, MP1 calls $0.50, 1 fold, Hero calls $0.50, Button raises to $1, 1 fold, BB calls $0.50, UTG+1 calls $0.50, MP1 calls $0.50, Hero calls $0.50.

Flop: ($5.25) A, 4, J (5 players)
BB checks, UTG+1 checks, MP1 checks, Hero checks, Button checks.

Turn: ($5.25) 5 (5 players)
BB checks, UTG+1 bets $1, MP1 folds, Hero raises to $4, Button folds, BB folds, UTG+1 calls $3.

River: ($13.25) A (2 players)
UTG+1 bets $10, Hero folds.

Final Pot: $23.25

Results in white below:
UTG+1 doesn't show.
Outcome: UTG+1 wins $23.25.

I dont think he would bet out with Ax because of the flush, he might've had 2 pair on the turn?

That's a donk flush. Hit it on the turn and check it.