Opponent is slightly loose and aggressive. he's also a slight loser over a few hundred hands.

21% vp$ip.
11% PFR
PFAF - 2.5

3x BB had been a standard opening raise for him on a couple of the hands i had seen him play.

i think i made a big mistake checking behind him on this river. however, i couldn't imagine many hands that would call me that i could beat short of AJs or KJs. still, with this much invested already, anyone think i turned into a big baby with my check?

Anyone think my turn bet or flop raise was too weak?

PokerStars No-Limit Hold'em, $4 BB (8 handed)

MP1 ($393.80)
MP2 ($475.75)
Hero ($400)
Button ($619.75)
SB ($378)
BB ($123.60)
UTG ($493.70)
UTG+1 ($957.20)

Preflop: Hero is CO with , .
2 folds, MP1 raises to $12, 1 fold, Hero calls $12, 2 folds, BB calls $8.

Flop: ($38) , , (3 players)
BB checks, MP1 bets $30, Hero raises to $80, BB folds, MP1 calls $50.

Turn: ($198) (2 players)
MP1 checks, Hero bets $125, MP1 calls $125.

River: ($448) (2 players)
MP1 checks, Hero checks.

Final Pot: $448

Results in white below:
MP1 has Ks Js (one pair, jacks).
Hero has Qs Qd (one pair, queens).
Outcome: Hero wins $448.

i think you played this hand correctly
you're not getting called by anything that you dont beat on that river, if hes a halfway decent player anyway.
but then again, i am an idiot, so you may wanna look for input from someone knowledgeable

I don't bet that river although I do think someone with AJ or KJ will call. Any real bet will pot commit you if he raises so if you aren't willing to put it all in, don't bet.

I think you played it right but I'm also a little weak on the river. So unless he's pretty passive and will play KK or AA this way, you should be good. I don't bet the river but I think it should be bet.

I think you have to bet here with position. I would check this river out of position, but once he checks I would bet this. I put him on a pair and a draw. I think you have two options on this river... a value bet or a large "steal" bet. If he is a decent player with TPTK he might call your steal attempt. If he is a crappy player he might still call. A good player will fold KJ on down and any pure draw. A bad player will call you with any pair here I think, certainly to a value bet. I would be extremely surprised to see a raise of my bet here, and would certainly be willing to put all my money into this pot if that was the case. If he hit a miracle two-pair on the river I pay him off. If he had trips the whole time or called you down to the river with pocket deuces, I pay him off, promptly re-buy, and hopefully take his stack. Either way I think a bet on the river here is +ev.