I'll give a short analysis too, if you don't mind, just because it helps me understand the game better myself.

I think you made a mistake by allowing darth_ender's queen a huge amount of coverage on the board. At turn 3, he set himself up to move into the centre of the board. The fact that he risked his knight to take a pawn makes that apparent. He was baiting you so he could get out in the open. Once he was on d5 on turn 5 he was covering more than half the board with his queen and was in a position to move just about wherever he wanted. You forced him out of that position with your knight, but he moved into you territory. You did a good job getting him out of there, but then he started moving bishops around, taking over the centre of the board. Around turn 9, it might have been wise to move your knight out to defend against his oncoming pieces, but you ended up making a line of defense on row 3 instead. I think this was probably a bad idea since it allowed ender to trap you. After that there wasn't much you could do to effectively come back.

Hopefully that's accurate and I didn't sound too critical.