I've done the same many times. It's called having too much faith in your opponent.
My best blunder ever

I've done the same many times. It's called having too much faith in your opponent.

I've done the same many times. It's called having too much faith in your opponent.
Really crazy uh
When I saw 14... Qa4 on the game I was thinking: well, he wants to kick out my knight on c3 to play Qxa2. And then I think: But hey, that's really slow and is not a real problem so I'm going to proceed with my plans with 15. Rdg1 lol

It would have been funny if he left his queen where she was, and continue with 15... b5. Would I have taken the queen then, would I have noticed?

I am so used to Nd4 that I did not see it until ... Qc7 when my first thought was wasting a tempo ;-)
I just played this game. Time control was 15|10. Although it is one of the most precise games I have played to date, I wasted an opportunity more than obvious (I was focus on the other side of the board I guess). When I analyzed the game after finishing it I was shocked. I have +1900 in TT and yes, it looks like it's just a number.
Find the blunder of white.