Youch. It's sad how many people write off Mass Effect or BioWare in general based on the ending of ME3. Whatever train wreck that was, the games are still awesome until that point. They certainly didn't deserve what the last 15 minutes made of the series. 
Yet I can't blame him. It was years of waiting (even more than me, since I player ME3 when it was just out) and preparation playng many different runs at ME1/2.
The problem is, the ending is something people have played for for three games, Is the biggest delusion one can have after having played for all those hours, the ending should be the reward of all those hours of shooting and running.
I'm now less angry at the tricolor ending, but it took me years. And even now, I can't really think of buyng another ME game ever. The scar is there, and is deep.