Somehow I can not post to the cash game analysis section so here we go:

We have not played much with villain but I think he is a regular.

Is this just purely a bad play?

PokerStars Hand #196597683407: Hold'em No Limit ($0.02/$0.05 USD) - 2019/02/03 16:01:09 ET

Table 'Doris II' 6-max Seat #2 is the button

Seat 1: skromezowo ($5.04 in chips)

Seat 2: uvilnis ($8.72 in chips)

Seat 3: mikuder ($5.02 in chips)

Seat 4: Jelieva ($5.07 in chips)

Seat 5: dirtyhary630 ($9.93 in chips)

mikuder: posts small blind $0.02

Jelieva: posts big blind $0.05

*** HOLE CARDS ***

Dealt to mikuder [3d 4d]

dirtyhary630: folds

skromezowo: folds

uvilnis: folds

mikuder: raises $0.10 to $0.15

Jelieva: calls $0.10

*** FLOP *** [2d Qc 8h]

mikuder: checks

Jelieva: checks

*** TURN *** [2d Qc 8h] 8♦

mikuder: bets $0.10

Jelieva: raises $0.35 to $0.45

mikuder: raises $0.65 to $1.10

Jelieva: calls $0.65

*** RIVER *** [2d Qc 8h 8d] 6♣

mikuder: bets $3.77 and is all-in

I think you might know it by now, but I would never play 3d4d against anyone, especially a regular, even on SB.

The river bluff makes sense, but not all-in.

Yes. Fold pre.

What was your thought process for 3betting his turn raise? Try to think about your hand every step of the way and be able to answer the question, "Why am I calling/raising/folding?"

Very strangely played, especially with an unknown opponent.

for a river bluff, I see a board that is too weak. No draw cards for preflop play closed. The only thing you (and the villain) can have on this board is the pocket pair that received the third card (and the full house with 88 on the turn). But this is not an obvious hand to successfully bluff into it. At the same time, there is a rather big risk that your villain has just such a hand and rejoices, seeing as you yourself give him your money.

at those stakes Yes it is a bad play. You will called with just about anything, Once reraised you know they got some of it. At best he has a Q like KQ, QJ, QT

total spazz.

fold preflop unless you have overfolding guy to steals on BB.
as played check on flop. Turn bet doesn't make any sense. What do you bet there 1/3 ? your range is always weak there. And if you 3bet there you always look bluffy because you never have a good hand there. Just think about your range and how would you play your value range. Your action doens't make any sense.

I agree that 43s should be folded pre.
Postflop: It is a blind battle and things can always get a little out of hand here. But if my opponent raises on a board pairing turn i would just comfortably fold.

So you should never have arrived on the river in the first place. On the river itself you are at the absolute bottom of your range.
But i would prefer to bluff with a hand like 97, that would block some of opponents most likely trips. Perhaps ranges are so strong here that you should only bluff with a week Queen also blocking some full houses. So Q7, Q9 are the best bluffs i think.
But that is if your opponent is ever folding and on NL5 i dont see anyone folding a strong Q or an 8 here......

You should have probably been grateful about the raise on the turn. That could have saved you a tough river spot. If you had had a better draw it would not be so simple

Also think about the value bets in your range: Some boats and the quads dont make too much sense with the check on the flop (22 and 88 should be mandatory C-bets) and the 3bet on the turn (would you really do that with QQ or Q8?), which leaves A8 and K8 as the hands you are representing the most. 86s has only one combo and should be called on the turn anyway

just bad bluff

I'll agree with most on weirdly played but I actually kinda like it if you think this guy is going to raise light in that spot on your delayed c-bet. A check flop and 3bet turn is super strong, BB probably thinks it's very likely you have an 8...and then calls the 3bet anyways. Maybe BB has a strong draw like J 9 diamonds. More likely is he has a suited 8 with a decent kicker and will probably call your river allin at these stakes. If you're trying to make a draw fold, you could bet much smaller and achieve the same result.

There is a pair on the board, so your outs are not clean. Also, you are not drawing the nut flush. You bet too little on the Turn. Generally speaking, trying to bluff people in 5NL, is not the way to beat these stakes..