How did I lose? I am not sure how this is supposed to work

I am fairly new to this site. I created my account many years ago but never played here until recently. I have spent most of my time doing the lessons, playing puzzles and watching videos. 

Tonight I decided I would play another person for the first time. 

The game lasted about 5 moves, I made my last move then the timers stopped counting down and started flashing. This lasted for about a full minute then suddenly it said the other person won because I abandoned the game?

I am confused because on my screen the other player never moved. As soon as it said he won, it showed one of his pieces in a different spot.

https://support.chess.com/article/213-how-do-i-fix-my-disconnect-lag-issues

I didn't even consider this to be a possibility because I never have lag issues or disconnect issues anywhere else. But I do tend to keep a lot of tabs open for various reasons so maybe that was the issue. Thank you for your response. I do appreciate it.