Representing the royal?

Does this kind of thing happen often to everyone, or am I giving off signals that I'm weak-tight (or both)?

Villain is loose preflop (about normal raising range, but if it's got paint, it plays), and aggressive, a little tricky, but but not crazy postflop. We played for a while HU when the original batch of loosies left the table with neither having a clear edge. He's tried bluffing with a raise once or twice after the board paired, but nothing like this.

Party Poker 3/6 Hold'em (6 max, 6 handed) FTR converter on zerodivide.cx

Preflop: Hero is SB with Q[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/club.gif[/img].
<font color="#666666">1 fold</font>, MP calls, <font color="#666666">2 folds</font>, Hero completes, BB checks.

Flop: (3 SB) K[img]/images/graemlins/heart.gif[/img], T[img]/images/graemlins/heart.gif[/img], Q[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, <font color="#CC3333">BB bets</font>, MP calls, <font color="#CC3333">Hero raises</font>, <font color="#CC3333">BB 3-bets</font>, MP folds, <font color="#CC3333">Hero caps</font>, BB calls.

Turn: (6 BB) Q[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">BB raises</font>, <font color="#CC3333">Hero 3-bets</font>, BB calls.

River: (12 BB) K[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">BB raises</font>, <font color="#CC3333">Hero 3-bets</font>, BB folds.

Final Pot: 17 BB

(Yes, I probably should have raised preflop with KQ, and normally I do. Villain may have not tried so hard if I'd have raised, but how then would he have put me on something by the river 3-bet that would make him fold for one more bet?)

I know it's probably useless to try and get my head around this, but it seems to be happening more and more (one common example: the donk on every street, despite getting raised each time). It's like they read the line in HEPFAP about how the one who bets/raises the most has the advantage, and then stop reading.