How is that possible? You can't lose if he doesn't reconnect! There's a time limit you have to wait out. If your opponent doesn't reconnect within that time limit , he's disqualified and you're declared the winner!
The only way you lose is if you're not patient enough to wait and you leave..... resulting in YOU technically forfeiting the match and being declared the loser.
You have to be patient and wait for the opponents reconnect timer to run out.