Teammates conceding defeat in MM

Is it just me, or do I loose if my n00bish teammate concedes defeat as soon as just 1 minor thing doesnt work for him?

I played this battle today, where i was teamed up with a 2 star. I started the battle with a missile skirmish, and then brought my infantry in. My teammate then charged his cav in the fight. They got desimated. Even tough he lost his cav, I was still winning the fight. He brought his infantry in, and they too got destroyed. He then had no units left in the battle. I was still holding the enemy, and the fight was far from over

Because my teammate lost all of his units, he conceded defeat, and in the midst of battle, the popup said it was a "costly enemy victory"... WTF??? The fight was far from over??