Taking advantage, ethical question

[TheGrifter]

This situation arose in a Live Casino NL game. I was sitting at a table where I recognized a few regular faces but knew no one. A young asian kid who was sitting next to me started chatting with me and we talked for most of the 12 hours I was there.

After a few hours the kid says, I hope we don't get involved in too many pots together, I don't want to take your money. I responded that he seemed like a nice guy but I was going to do everything in my power to send him to the felt.

The funny thing is, as play continued it seemed that he wasn't just talking. If we were HU in a pot he would generally check it down after the flop and my raises were getting absolute respect. I play tight anyway, so it is possible that he simply didn't want to get involved against my possible range of holdings, however he was generally rather loose/aggressive so I think it was more than that.

Of course I started to use this to my advantage and took a good chunk of change from him, checking my draws to get free cards and bluffing liberally. Does anyone see anything wrong with using the psychological edge that you have against a player that "likes" you?